Wireless communication terminal, wireless communication base station, wireless communication system, and reporting method

ABSTRACT

In a wireless communication terminal in a wireless communication system for performing a control not to transmit signals, or to transmit signals with a reduction in a transmission power by a part of radio resources for a downlink signal in a cell provided by a base station, the terminal receives control information in generating a report related to a measurement result of the cell provided by the base station, monitors a state of a radio link with an own cell, and performs measurement on reception of the downlink signal. If an instruction for restricting the measurement to a part of the radio resources is included in the control information from the base station after the radio link failure occurs, the terminal generates and transmits a radio link failure report including the measurement result in the radio resources as instructed when the radio link failure occurs.

TECHNICAL FIELD

The present invention relates to a wireless communication system thatreduces a traffic volume in transmission to a wireless communicationterminal, or reduces a transmission power of a wireless signal, and awireless communication terminal and a wireless communication basestation used in the wireless communication system, and a reportingmethod for the wireless communication terminal.

BACKGROUND ART

Standards Body 3GPP (The 3rd Generation Partnership Project) advancesthe standardization of LTE-Advanced (Long Term Evolution Advanced:LTE-A) as an LTE (long Term Evolution) system-compatible next-generationcommunication standard. In the LTE, a wireless communication basestation (E-UTRAN NodeB: eNB) of a network (Evolved Universal TerrestrialRadio Access Network (E-UTRAN) provides one or more communication cells.A wireless communication terminal (User Equipment: UE) belongs to one ofthe communication cells. Hereinafter, the wireless communication basestation (eNB) is called merely “base station”, the communication cell iscalled merely “cell”, and the wireless communication terminal (UE) iscalled merely “terminal”.

In the LTE, in order to perform self-optimization of the network (SelfOptimizing Network: SON), the terminal provides information at the timeof radio link failure (Radio Link Failure: RLF) to the base station. Theterminal detects the radio link failure (RLF) in the following threecases.

1. When an instruction of out-of-sync (out-of-sync) is continuouslydetected N310 times in a physical layer, a count of a given time T310starts. Then, if in-sync is not continuously detected in the physicallayer N311 times, T310 expires, and the terminal detects the RLF. Thevalues of T310, N310, and N311 are notified the terminal of from thebase station. If those values are not notified, the terminal uses apredetermined value.

2. When a random access problem (Random Access Problem) is instructedfrom a media access control (Media Access Control: MAC) layer, theterminal detects the RLF.

3. Arrival at the maximum number of retransmission is instructed from aradio link control (Radio Link Control: RLC) layer, the terminal detectsthe RLF.

When the terminal maintains an AS security (Access Stratum Security)when detecting the radio link failure (RLF), the terminal starts an RRCconnection reestablishment (Radio Resource Control ConnectionRe-establishment: RRC Connection Re-establishment).

FIG. 12 is a timing chart when the terminal performs the RRC connectionreestablishment. Upon detecting the radio link failure (RLF), theterminal detects a suitable cell (Suitable Cell) with the use of cellselecting means, and selects the cell. Then, the terminal transmits anRRC connection reestablishment request message (RRC ConnectionReestablishment Request) to the base station of the cell selected by thecell selection. Upon receiving the RRC connection reestablishmentrequest message from the terminal, the base station determines whetherto accept the RRC connection reestablishment request message of theterminal, or not. When determining to accept the terminal, the basestation transmits an RRC connection reestablishment message (RRCConnection Reestablishment) to the terminal. Upon receiving the RRCconnection reestablishment message, the terminal generates an RRCconnection reestablishment complete message (RRC ConnectionReestablishment Complete). If RLF information related to the RLF thathas been finally generated is available, the terminal includes an RLFinformation available flag (rlf-InfoAvailable) in the RRC connectionreestablishment complete message, and sets the flag as true (true). Theterminal transmits the RRC connection reestablishment complete messageto the base station. With the above operation, the terminal performs theRRC connection reestablishment.

FIG. 13 is a timing chart illustrating an example in which the terminalprovides the information at the time of the radio link failure to thebase station. The terminal transmits the RRC connection reestablishmentcomplete message in which the RLF information available flag(rlf-InfoAvailable) is included, and the flag is set to the true (true),to the base station. The base station receives the RRC connectionreestablishment complete message in which the RLF information availableflag is set to the true (true). The base station determines whether theinformation from the terminal at the time of the radio link failure isnecessary, or not. When determining that the information from theterminal is necessary, the base station transmits a terminal informationrequest message (UEInformationRequest) in which an RLF report requestflag (rlf-ReportReq) is set to the true (true) to the terminal in orderto request transmission of the information at the time of the radio linkfailure to the terminal. The terminal receives a terminal informationrequest message in which the RLF report request flag Z (rlf-ReportReq)is set to the true (true). The terminal generates an RLF report(rlf-report), generates a terminal information response message (UEInformation Response) in which the RLF report (rlf-report) is included,and transmits the terminal information response message to the basestation.

FIG. 14 is a diagram illustrating an example of a configuration of theRLF report (rlf-report). As illustrated in FIG. 14, the RLF report(rlf-report) is configured by a measurement result of an own cellfinally connected, and a measurement result of a neighbor cell at thetime of generating the RLF. The measurement result of the own cellincludes a received power (Reference Signal Received Power: RSRP) or areceived quality (Reference Signal Received Quality: RSRQ). On the otherhand, the measurement result of the neighbor cell is listed for eachradio access technology (Radio Access Technology: RAT), and furtherlisted for each frequency. The respective lists are arranged in orderfrom the best cell of the measurement result at the time of generatingthe RLF. The terminal is set to measure the frequency of the radioaccess technology which needs to be measured. The measurement resultincluded in the RLF report (rlf-report) is intended for the cell of thefrequency of the radio access technology which has been set to bemeasured (measurement) by the terminal.

The base station or the network can optimize the network on the basis ofthis information.

In the LTE-A, as a method of an inter-cell interference coordination(Inter-cell Interference Coordination: ICIC), an almost blank subframe(Almost Blank Subframe: ABS) is used for control to prevent aninterference between cells in a time domain to protect a resource. Inthis control, with the provision of a period during which the basestation does not transmit the signal, or the transmission power isreduced, to thereby reduce an interference affecting a communicationbetween the other base station and the terminal.

The ABS is characterized by the following elements.

In the ABS a cell specific reference signal (Cell Specific ReferenceSignal: CRS) is always transmitted.

If the ABS matches a multimedia broadcast multicast service singlefrequency network (Multimedia Broadcast multicast service SingleFrequency Network: MBSFN) subframe, the CRS is not transmitted in a datadomain.

If the timing of the ABS matches with a primary synchronization signal(Primary Synchronization Signal: PSS), a secondary synchronizationsignal (Secondary Synchronization Signal: SSS), a physical broadcastchannel (Physical Broadcast Channel: PBCH), a system information blocktype 1 (System Information Block Type 1: SIB1), paging (Paging), or apositioning reference signal (Positioning Reference Signal: PRS), theyare transmitted.

In the ABS, a channel state information reference signal (Channel StateInformation Reference signal: CSI-RS) can be transmitted.

When the MBSFN subframe is included in the pattern of the ABS, the MBSFNsubframe can be used for the time domain inter-cell interferencecoordination. An example of the method of using the ABS having the abovefeatures will be described below.

In FIG. 15, (a) and (b) are diagrams illustrating an example using theABS. As illustrated in FIG. 15, in addition to a cell arrangementcentered on a macrocell in which a coverage area of the cell is wide, anetwork in which a low power node (Low Power Node: LPN) in which thecoverage area of the cell is narrow is arranged within the macrocell hasbeen studied in order to efficiently cover a local area such as anindoor facility a large volume of traffic is concentrated. The low powernode is configured by a cell that is managed by a relay node (RelayNode: RN), a picocell that has the same function as that of themacrocell, and is low in the transmission power, or a CSG (ClosedSubscriber Group) cell that can be connected with only a specific memberwithout provision of an interface (X2 interfaces) between the basestations.

FIG. 15(a) illustrates an example in which the picocell is arrangedwithin the coverage of the macrocell on the same frequency. For example,the time domain inter-cell interference coordination is used by theterminal that is being connected by the picocell, which is located at anend of the picocell. For example, the time domain inter-cellinterference coordination is used to distribute a load of the macrocellinto the picocell. In order to protect the specific subframe of thepicocell from an interference with the macrocell, the ABS is used by themacrocell. The terminal connected to the picocell performs a radioresource measurement (Radio Resource Measurement: RRM) for a movementcontrol, a radio link monitoring (Radio Link Monitoring: RLM), and achannel state information measurement (Channel State Informationmeasurement: CSI measurement) with the use of the protected resource.The terminal can know the protected resource by allowing a measurementresource restriction (Measurement Resource Restriction) to be notified.As a result, a measurement precision of the picocell under a stronginterference with the macrocell can be enhanced by the measurement attiming when the interference with the macrocell is reduced. That is, arange of the picocell can be widened, the connection with the picocellis easily maintained, and the load distribution can be performed.

Also, the terminal that is being connected to the neighbor cell measuresthe picocell with the use of a measurement resource restriction(Measurement Resource Restriction), thereby being capable of enhancingthe measurement precision of the picocell under the strong interferencewith the macrocell. As a result, handover (handover) of the connectionto the picocell is easily performed, and the load distribution can beperformed.

FIG. 15(b) illustrates an example in which the CSG cell is arrangedwithin the coverage of the macrocell. For example, the time domaininter-cell interference coordination is used by the terminal that isbeing connected to the macrocell located on an end of the CSG cell. Forexample, the terminal that is not allowed to be connected to the CSGcell is used for maintaining the connection with the macrocell.

The CSG cell uses the ABS to reduce the interference, thereby beingcapable of protecting the subframe of the specific macrocell from theinterference. The terminal that is not allowed to be connected to theCSG cell is notified of the protected resource as the measurementresource restriction, and can continue to be connected to the macrocellunder the strong interference with the CSG cell by the measurement atthe timing when the interference with the CSG cell is reduced. Themeasurement contents include RRM, RLM, and CSI.

CITATION LIST Non-Patent Literature

-   Non-patent Literature 1: 3GPP TS36.300 v10.2.0, “Evolved Universal    Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial    Radio Access Network (E-UTRAN)”-   Non-patent Literature 2: 3GPP TS36.331 v10.0.0, “Evolved Universal    Terrestrial Radio Access (E-UTRA) Radio Resource Control (RRC)”

SUMMARY OF INVENTION Technical Problem

Under the environments where the ABS is used, a precision in themeasurement is different between a value measured in the subframe of theABS and a value measured in the subframe which is not the ABS.Therefore, in the conventional RLF report (rlf-report), there arisessuch a problem that a precision with which the base station grasps thestate of the terminal is reduced.

An object of the present invention is to provide a wirelesscommunication terminal, a wireless communication base station, awireless communication system, and a reporting method, in which anexternal device can precisely grasp a state in which the radio linkfailure occurs in the wireless communication terminal even in theenvironment where the ABS is used.

Solution to Problem

The present invention provides a wireless communication terminal used ina wireless communication system for performing a control not to transmitsignals, or to transmit signals with a reduction in a transmission powerin a part of radio resources for a downlink signal in a communicationcell provided by a wireless communication base station, the wirelesscommunication terminal including: a receiver that is configured toreceive control information referred to in generating a report relatedto a measurement result of the communication cell provided by thewireless communication base station; a radio link monitoring sectionthat is configured to monitor a state of a radio link with an own cellwhich indicates a communication cell in connection; a measurementsection that is configured to perform a measurement on a reception ofthe downlink signal in the communication cell provided by the wirelesscommunication base station; a report generator that is configured togenerate a radio link failure report including a measurement result whena radio link failure occurs in the own cell; and a transmitter that isconfigured to transmit the radio link failure report, wherein if aninstruction for restricting measurement to a part of the radio resourcesis included in the control information from the wireless communicationbase station after the radio link failure occurs, the report generatorgenerates the radio link failure report including a measurement resultin the radio resources as instructed when the radio link failure occurs.

The present invention provides a wireless communication terminal used ina wireless communication system for performing a control not to transmitsignals, or to transmit signals with a reduction in a transmission powerin a part of radio resources for a downlink signal in a communicationcell provided by a wireless communication base station, the wirelesscommunication terminal including: a receiver that is configured toreceive control information related to restriction of the radioresources for an own cell or a neighbor cell to be measured, from thewireless communication base station; a measurement section that isconfigured to receive a reference signal in the own cell or the neighborcell, and to perform a measurement on reception of the downlink signal;a report generator that is configured to generate a radio link failurereport including a result of the measurement; and a transmitter that isconfigured to transmit the radio link failure report, wherein if aninstruction for restricting the measurement of the own cell or theneighbor cell to a part of radio resources is included in the controlinformation from the wireless communication base station, the reportgenerator generates the radio link failure report including ameasurement result of the own cell or the neighbor cell in the radioresources as instructed.

The present invention provides a wireless communication base stationused in a wireless communication system for performing a control not totransmit signals, or to transmit signals with a reduction in atransmission power in a part of radio resources for a downlink signal ina communication cell provided by the wireless communication basestation, the wireless communication base station including: a receiverthat is configured to receive a radio link failure report including ameasurement result restricted to the part of radio resources, from awireless communication terminal used in the wireless communicationsystem; and a controller that is configured to determine whether or notthe received radio link failure report is the measurement restricted tothe part of radio resources.

The present invention provides a wireless communication base stationused in a wireless communication system for performing a control not totransmit signals, or to transmit signals with a reduction in atransmission power in a part of radio resources for a downlink signal ina communication cell provided by the wireless communication basestation, the wireless communication base station including: a receiverthat is configured to receive a radio link failure report including ameasurement result in an own cell or a neighbor cell, which isrestricted to the part of radio resources, from a wireless communicationterminal used in the wireless communication system; and a controllerthat is configured to determine whether or not the received radio linkfailure report is the measurement result restricted to the part of radioresources.

The present invention provides a wireless communication system forperforming a control not to transmit signals, or to transmit signalswith a reduction in a transmission power in a part of radio resourcesfor a downlink signal in a communication cell provided by first andsecond wireless communication base stations, wherein the first wirelesscommunication base station transmits control information referred to bya wireless communication terminal in generating a report related to ameasurement result of the communication cell provided by the firstwireless communication base station, the wireless communication terminalincludes: a receiver that is configured to receive the controlinformation; a radio link monitoring section that is configured tomonitor a state of a radio link with an own cell which indicates acommunication cell in connection; a measurement section that isconfigured to perform a measurement on a reception of the downlinksignal in the communication cell provided by the first wirelesscommunication base station; a report generator that is configured togenerate a radio link failure report including a measurement result whena radio link failure occurs in the own cell; and a transmitter that isconfigured to transmit the radio link failure report, wherein if aninstruction for restricting measurement to a part of the radio resourcesis included in the control information from the first wirelesscommunication base station after the radio link failure occurs, thereport generator generates the radio link failure report including ameasurement result in the radio resources as instructed when the radiolink failure occurs, and the second wireless communication base stationincludes: a receiver that is configured to receive, from the wirelesscommunication terminal, the radio link failure report including ameasurement result restricted to the part of radio resources, generatedby the wireless communication terminal; and a controller that isconfigured to determine whether or not the received radio link failurereport is the measurement restricted to the part of radio resources.

The present invention provides a wireless communication system forperforming a control not to transmit signals, or to transmit signalswith a reduction in a transmission power in a part of radio resourcesfor a downlink signal in a communication cell provided by first andsecond wireless communication base stations, wherein the first wirelesscommunication base station transmits control information related torestriction of the radio resources when a wireless communicationterminal measures an own cell or a neighbor cell which indicates a cellprovided by the first wireless communication base station, to thewireless communication terminal, the wireless communication terminalincludes: a receiver that is configured to receive the controlinformation; a measurement section that is configured to receive areference signal in the communication cell provided by the firstwireless communication base station, and to perform a measurement onreception of the downlink signal; a report generator that is configuredto generate a radio link failure report including a result of themeasurement; and a transmitter that is configured to transmit the radiolink failure report, wherein if an instruction for restricting themeasurement of the own cell or the neighbor cell to a part of radioresources is included in the control information from the first wirelesscommunication base station, the report generator generates the radiolink failure report including a measurement result of the own cell orthe neighbor cell in the radio resources as instructed, and the secondwireless communication base station includes: a receiver that isconfigured to receive, from the wireless communication terminal, theradio link failure report including a measurement result in an own cellor a neighbor cell, which is restricted to the part of radio resources,generated by the wireless communication terminal; and a controller thatis configured to determine whether or not the received radio linkfailure report is the measurement result restricted to the part of radioresources.

The present invention provides a reporting method of a wirelesscommunication terminal used in a wireless communication system forperforming a control not to transmit signals, or to transmit signalswith a reduction in a transmission power in a part of radio resourcesfor a downlink signal in a communication cell provided by a wirelesscommunication base station, the reporting method including: receivingcontrol information referred to in generating a report related to ameasurement result of the communication cell provided by the wirelesscommunication base station; monitoring a state of a radio link with anown cell which indicates a communication cell in connection; performinga measurement on a reception of the downlink signal in the communicationcell provided by the wireless communication base station; if aninstruction for restricting measurement to a part of the radio resourcesis included in the control information from the wireless communicationbase station after the radio link failure occurs in the own cell,generating a radio link failure report including a measurement result inthe radio resources as instructed when the radio link failure occurs;and transmitting the radio link failure report.

The present invention provides a reporting method of a wirelesscommunication terminal used in a wireless communication system forperforming a control not to transmit signals, or to transmit signalswith a reduction in a transmission power in a part of radio resourcesfor a downlink signal in a communication cell provided by a wirelesscommunication base station, the reporting method including: receivingcontrol information related to restriction of the radio resources for anown cell or a neighbor cell to be measured, from the wirelesscommunication base station; receiving a reference signal in the own cellor the neighbor cell, and performing a measurement on reception of thedownlink signal; generating a radio link failure report including aresult of the measurement; and transmitting the radio link failurereport, wherein if an instruction for restricting the measurement of theown cell or the neighbor cell to a part of radio resources is includedin the control information from the wireless communication base station,the radio link failure report is generated to include a measurementresult of the own cell or the neighbor cell in the radio resources asinstructed.

Advantageous Effects of Invention

According to the wireless communication terminal, the wirelesscommunication base station, the wireless communication system, and thereporting method according to the present invention, the external devicecan precisely grasp the state in which the radio link failure occurs inthe wireless communication terminal even in the environment where theABS is used.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a timing chart when a terminal transmits an RLF report in awireless communication system according to a first embodiment.

FIG. 2 is a block diagram of the terminal configuring the wirelesscommunication system according to the first embodiment.

FIG. 3 is a block diagram of a base station configuring the wirelesscommunication system according to the first embodiment.

FIG. 4 is a flowchart illustrating an example of the operation of theterminal according to the first embodiment.

FIG. 5 is a timing chart when a terminal transmits an RLF report in awireless communication system according to a second embodiment.

FIG. 6 is a block diagram of the terminal configuring the wirelesscommunication system according to the second embodiment.

FIG. 7 is a block diagram of a base station configuring the wirelesscommunication system according to the second embodiment.

FIG. 8 is a flowchart illustrating an example of the operation of theterminal according to the second embodiment.

FIG. 9 is a timing chart when a terminal transmits an RLF report in awireless communication system according to a third embodiment.

FIG. 10 is a block diagram of the terminal configuring the wirelesscommunication system according to the third embodiment.

FIG. 11 is a flowchart illustrating an example of the operation of theterminal according to the third embodiment.

FIG. 12 is a timing chart when the terminal reestablishes the RRCconnection.

FIG. 13 is a timing chart illustrating an example in which the terminalprovides information at the time of the radio link failure to the basestation.

FIG. 14 is a diagram illustrating an example of a configuration of anRLF report (rlf-report).

In FIG. 15, (a) and (b) are diagrams illustrating an example in whichthe ABS is used.

FIG. 16 is a timing chart when a terminal transmits a logged measurementreport in a wireless communication system according to a fourthembodiment.

FIG. 17 is a block diagram of the terminal configuring the wirelesscommunication system according to the fourth embodiment.

FIG. 18 is a block diagram of the base station configuring the wirelesscommunication system according to the fourth embodiment.

FIG. 19 is a flowchart illustrating an example of the operation of theterminal according to the fourth embodiment.

FIG. 20 is a flowchart illustrating an example of the operation of theterminal according to the fourth embodiment.

DESCRIPTION OF EMBODIMENTS

A wireless communication system according to embodiments of the presentinvention will be described in detail with reference to the drawings.The wireless communication system according to the embodiments whichwill be described below includes at least one wireless communicationterminal, and at least one wireless communication base station that cancommunicate with the wireless communication terminal through a wirelesscommunication network. In the following description, the wirelesscommunication terminal is called simply “terminal”. The terminal is, forexample, a cellular phone. Also, the wireless communication base stationis called simply “base station”. The base station is a base station thatcan be wirelessly connected to the terminal, which is a generic termincluding, for example, a macro base station that manages a macrocell, apico base station that manages a picocell, a remote radio head (RemoteRadio Head: RRH) located in an area distant from the base station, arelay device (relay node or repeater) wirelessly connected to the basestation, and a CSG base station that manages a CSG cell.

The wireless communication system uses a mobile communication technologyof an LTE or an LTE-A standardized by 3GPP (The 3rd GenerationPartnership Project). The mobile communication technology used by thewireless communication system is not limited to the above standards, butmay be a wireless LAN (Wireless Local Area Network), WiMAX (WorldwideInteroperability for Microwave Access) such as IEEE802.16, IEEE802.16e,or IEEE802.16m, 3GPP2, SAE (System Architecture Evolution), UMTS(Universal Mobile Telecommunications System), or a 4th generation mobilecommunication standard.

Each of the wireless communication base stations configures at least onecommunication cell. The communication cell means a wireless networkobject that can be uniquely identified by the terminal on the basis of adifference in identifiers allocated to geographical areas or frequenciesused in the geographical areas. In the following description, thecommunication cell is called simply “cell”. One or more cells areconfigured by one wireless communication base station for each of one ormore carrier frequencies. The above configuration represents a basicconcept, and the wireless communication base station may configure onecell in cooperation with another wireless communication base station.Also, the terminal performs a communication by the aid of at least onecell configured by the wireless communication base station.

Hereinafter, the wireless communication system according to first tofourth embodiments will be described below in order. In the first tofourth embodiments, the configurations having the same function aredenoted by identical reference symbol, and redundant descriptions willbe omitted.

First Embodiment

A wireless communication system according to a first embodiment will bedescribed with reference to FIGS. 1 to 4. The wireless communicationsystem according to the first embodiment includes the terminal and thebase station described above. The terminal has a function of receiving areference signal transmitted from the base station for each cell in adownlink, and reporting a measurement result derived on the basis of agiven calculation expression to the base station. Also, the terminal hasa function of transmitting an RLF report to the base station when theRLF occurs. Each of the base stations allocates and manages a radioresource (for example, frequency band in a frequency domain or a timedomain) with respect to each of the terminals. Further, the base stationhas a function of an access point of the wireless access network for theterminal.

FIG. 1 is a timing chart when a terminal transmits the RLF report in thewireless communication system according to the first embodiment. Asillustrated in FIG. 1, a base station (first base station) connectedwith a terminal transmits an RRC connection reconfiguration message (RRCConnection Reconfiguration) to the terminal. The RRC connectionreconfiguration message includes control information and a measurementconfiguration (Measurement Configuration: MC). The control informationincludes measurement resource restrictions (Measurement ResourceRestriction) for measurement of the own cell and radio link monitoringif the occasion demands. The measurement resource restriction isinformation for specifying a resource to be measured by the terminal toenhance a measurement precision. For example, the measurement resourcerestriction is a technique used for the purpose of enhancing themeasurement precision. Also, for example, a specific resource instructedby the measurement resource restriction is a resource low in aninterference with the cell measured by the terminal. Also, for example,a specific resource instructed by the measurement resource restrictionis a resource (ABS) in which a signal that is transmitted in a neighborcell is reduced. Also, for example, a specific resource instructed bythe measurement resource restriction is a resource (other than ABS) inwhich the signal that is transmitted by the neighbor cell is notreduced.

Upon receiving the RRC connection reconfiguration message from the basestation, the terminal transmits an RRC connection reconfigurationcomplete message (RRC Connection Reconfiguration Complete) to the basestation. Also, the terminal performs measurement (Measurement) and radiolink monitoring on the basis of the control information and themeasurement configuration from the base station. Upon detecting theradio link failure (RLF), the terminal detects a suitable cell (SuitableCell) with the use of cell selecting means, and selects the cell. Then,the terminal transmits an RRC connection reestablishment request message(RRC Connection Reestablishment Request) to a base station (second basestation) selected by the cell selection.

Upon receiving the RRC connection reestablishment request message fromthe terminal, the base station determines whether to accept the RRCconnection reestablishment request of the terminal, or not. Upondetermining to accept the terminal, the base station transmits an RRCconnection reestablishment message (RRC Connection Reestablishment) tothe terminal. Upon receiving the RRC connection reestablishment message,the terminal generates the RRC connection reestablishment completemessage (RRC Connection Reestablishment Complete). If the RLFinformation related to the radio link failure (RLF) occurred at the lasttime is available, the terminal includes an RLF information availableflag (rlf-InfoAvailable) in the RRC connection reestablishment message,and sets the flag as true (true). The terminal transmits the RRCconnection reestablishment complete message to the base station.

As described above, the terminal completes the RRC connectionreestablishment. On the other hand, the base station receives the RRCconnection reestablishment complete message in which the RLF informationavailable flag is set to the true (true) from the terminal. The basestation determines whether the information from the terminal at the timeof the radio link failure is necessary, or not. When determining thatthe information from the terminal is necessary, the base stationtransmits the terminal information request message(UEInformationRequest) in which an RLF report request flag(rlf-ReportReq) is set to the true (true) to the terminal in order torequest the terminal to transmit the information at the time of radiolink failure. The terminal receives the terminal information requestmessage in which the RLF report request flag is set to the true. If themeasurement resource restriction (Measurement Resource Restriction) formeasurement of the own cell is included in the control informationreceived from the first base station, the terminal generates an RLFreport (rlf-report) including the value obtained by measuring the owncell with the use of the measurement resource restriction. The terminalgenerates a terminal information response message(UEInformationResponse) including the RLF report, and transmits themessage to the base station.

The RLF report includes the value obtained by measuring the own cellwith the use of the measurement resource restriction in addition to thevalue obtained by measuring the own cell without use of the measurementresource restriction. With this configuration, because the measurementresult when the measurement resource restriction is used can be comparedwith the measurement result when the measurement resource restriction isnot used, a gain obtained by using the measurement resource restrictioncan be calculated, and the network can be optimized.

Also, when the value obtained by measuring the own cell with the use ofthe measurement resource restriction is included in the RLF report, thevalue obtained by measuring the own cell without use of the measurementresource restriction may not be included. With this configuration,because the base station can grasp a state in which the terminal isactually used, the network can be optimized. Also, as compared with acase in which both of the measurement result of the own cell when themeasurement resource restriction is not used, and the measurement resultof the own cell when the measurement resource restriction is used areincluded in the RLF report, the size of the RLF report can be reduced.

When the value obtained by measuring the own cell with the use of themeasurement resource restriction is included in the RLF report, that thevalue is measured by using the measurement resource restriction may benotified with the use of the flag. With this configuration, because thebase station can explicitly know that the measurement result is thevalue measured by using the measurement resource restriction, the basestation can easily know that any state has been measured. This flag(hereinafter referred to as “measurement resource restriction flag”) maybe replaced with an instruction of one bit. With the exchange of themeasurement configuration information between the base stations, thebase station may grasp whether the measurement result is the valuemeasured with the use of the measurement resource restriction, or not.With the above configuration, the addition of signaling in the radioresource can be suppressed.

The above description is exemplary, and the RLF report may betransmitted by a technique other than the above technique. For example,the terminal transitions to an idle state (Idle) after having detectedthe RLF. Thereafter, when the connection is newly established, the RLFinformation available flag (rlf-InfoAvailable) may be set to the true(true) and included in an RRC connection setup complete message (RRCConnection Setup Complete), and transmitted to the base station. Withthe above configuration, because the base station can know that theterminal holds the RLF report, the base station transmits the terminalinformation request message in which the RLF report request(rlf-Reportreq) is set to the true to the terminal, and can obtain theterminal information response message including the RLF report(rlf-report) from the terminal.

In the system described above, the first base station and the secondbase station may be configured by an identical base station. Also, adestination of the RLF report (rlf-report) from the terminal is notlimited to the second base station, but may be another base station withwhich the terminal can communicate.

[Configuration of Terminal According to First Embodiment]

FIG. 2 is a block diagram of the terminal configuring the wirelesscommunication system according to the first embodiment. As illustratedin FIG. 2, the terminal according to the first embodiment includes areceiver 101, a controller 103, and a transmitter 105. The controller103 includes a measurement configuration manager 111, a measurementmanager 113, an RLM controller 115, a reconnection controller 117, anRLF report generator 119, and an RLF report manager 121. Also, themeasurement manager 113 includes an own cell measurement section 131, arestricted own cell measurement section 133, and a neighbor cellmeasurement section 135.

The receiver 101 receives system information or individual controlinformation through a downlink of the cell which is being used by theterminal according to an instruction from the controller 103. Thereceiver 101 outputs the received system information and individualcontrol information to the controller 103.

The receiver 101 receives a cell specific reference signal (Cellspecific Reference Signal: CRS) or a received signal strength indication(Received Signal Strength Indication: RSSI) of the own cell according toan instruction from the own cell measurement section 131 installed inthe measurement manager 113. The receiver 101 outputs the received CRSor RSSI to the own cell measurement section 131. Also, the receiver 101receives the CRS or the RSSI of the own cell in the specific resourceaccording to an instruction from the restricted own cell measurementsection 133 installed in the measurement manager 113 of the controller103. The receiver 101 outputs the received CRS or RSSI to the restrictedown cell measurement section 133. Also, the receiver 101 receives theCRS or the RSSI of the neighbor cell according to an instruction fromthe neighbor cell measurement section 135 installed in the measurementmanager 113 of the controller 103. The receiver 101 outputs the receivedCRS or RSSI to the neighbor cell measurement section 135 together with afrequency and the PCI. Further, upon receiving an instruction formeasurement of the CRS of the own cell from the RLM controller 115 ofthe controller 103, the receiver 101 receives the CRS of the own cell,and outputs the CRS to the RLM controller 115. Also, upon receiving aninstruction for measurement of the CRS of the own cell in the specificresource from the RLM controller 115, the receiver 101 receives the CRSof the own cell in the above resource, and outputs the CRS to the RLMcontroller 115.

The controller 103 outputs a measurement configuration (MeasurementConfiguration: MC), a physical cell identifier (Physical Cell ID: PCI)of the own cell, and the frequency of the own cell from the individualcontrol information to the measurement configuration manager 111. If themeasurement resource restriction for the own cell is included in theindividual control information, the controller 103 outputs themeasurement resource restriction for the own cell to the measurementconfiguration manager 111. The controller 103 outputs a response messageto the individual control information to the transmitter 105. If themeasurement resource restriction for the own cell is included in theindividual control information, the controller 103 outputs themeasurement resource restriction for the own cell and the configurationnecessary for the RLM to the RLM controller 115. Upon receiving the RRCconnection reestablishment message, the controller 103 outputs the abovemessage to the reconnection controller 117. When the terminalinformation request message (UEInformationRequest) in which the RLFreport request flag (rlf-ReportReg) is set to the true (true) is inputto the controller 103, the controller 103 instructs the RLF reportmanager 121 to transmit the RLF report.

The measurement configuration manager 111 outputs the PCI of the owncell, the frequency of the own cell, and the configuration necessary formeasurement of the own cell to the own cell measurement section 131.When the measurement resource restriction (Measurement ResourceRestriction) for the own cell is input to the measurement configurationmanager 111, the measurement configuration manager 111 outputs themeasurement resource restriction for the own cell, the PCI of the owncell, the frequency of the own cell, and the information necessary formeasurement of the own cell to the restricted own cell measurementsection 133. The measurement configuration manager 111 outputs theconfiguration necessary for measurement of the neighbor cell included inthe measurement configuration to the neighbor cell measurement section135 of the measurement manager 113.

The measurement manager 113 manages the RSRP and the RSRQ of the owncell in distinction between the RSRP and the RSRQ measured without theuse of the measurement resource restriction, and the RSRP and the RSRQmeasured with the use of the measurement resource restriction. Themeasurement manager 113 calculates the RSRQ according to the RSRP andthe received signal strength indication (Received Signal StrengthIndication: RSSI) which have been input from the own cell measurementsection 131, and manages the RSRP and the RSRQ as the RSRP and the RSRQof the own cell which have been measured without the use of themeasurement resource restriction. The measurement manager 113 calculatesthe RSRQ according to the RSRP and the RSSI which have been input fromthe restricted own cell measurement section 133, and manages the RSRPand the RSRQ as the RSRP and the RSRQ of the own cell which have beenmeasured with the use of the measurement resource restriction. Themeasurement manager 113 manages the RSRP and the RSRQ of the neighborcell for each PCI of the respective frequencies. When the measurementmanager 113 determines that the measurement of the neighbor cell isnecessary, according to the managed value and measurement configuration,the measurement manager 113 instructs the neighbor cell measurementsection 135 to measure the neighbor cell. The measurement manager 113calculates the RSRQ of the cell having the PCI of the above frequencyaccording to the RSRP, the RSSI, the PCI, and the frequency which havebeen input from the neighbor cell measurement section 135, and managesthe RSRP and the RSRQ.

In the same frequency, a common value may be used in the RSSI of the owncell and the neighbor cell, which has been measured without beingrestricted to the specific resource. Also, in the RSSI of the own cell,a common value may be used between the RSSI of the own cell measuredwithout being restricted to the specific resource, and the RSSI of theown cell measured with the use of the measurement resource restriction.

Upon receiving an instruction for outputting the held information fromthe RLF report generator 119, the measurement manager 113 outputs theheld RSRP and the RSQR of the respective cells to the RLF reportgenerator 119. In this situation, if the RSRP or the RSRQ which has beenmeasured with the use of the measurement resource restriction is presentin the own cell, the measurement manager 113 also outputs the aboveinformation to the RLF report generator 119. However, because themeasurement of the RSRQ is not essential, the own cell measurementsection 131, the restricted own cell measurement section 133, and theneighbor cell measurement section 135 may not input the RSSI to themeasurement manager 113. Therefore, the measurement manager 113 mayoutput only the RSRP of a part or all of the cells, which is output tothe RLF report generator 119, to the RLF report generator 119.

In order to measure the RSRP or the RSSI of the cell having the PCI ofthe frequency input from the measurement configuration manager 111, theown cell measurement section 131 instructs the receiver 101 to measurethe CRS or the RSSI. In order to remove an influence of fading from thevalue of the CRS or the RSSI which has been input from the receiver 101,the own cell measurement section 131 performs layer 3 filtering on thevalue input from the receiver 101, and outputs the calculated RSRP orRSSI to the measurement manager 113.

In order to measure the RSRP or RSSI of the cell having the PCI of theinput frequency in the resource instructed in the measurement resourcerestriction for the own cell which has been input from the measurementconfiguration manager 111, the restricted own cell measurement section133 instructs the receiver 101 to measure the CRS or the RSSI in theabove resource. The restricted own cell measurement section 133 performsthe layer 3 filtering on the CRS or RSSI input from the receiver 101,and outputs the calculated RSRP or RSSI to the measurement manager 113.

Upon receiving an instruction for measurement of the neighbor cell fromthe measurement manager 113, in order to measure the RSRP or RSSI of thecell having the frequency instructed in the measurement configuration,the neighbor cell measurement section 135 instructs the receiver 101 tomeasure the CRS or the RSSI. The neighbor cell measurement section 135receives the frequency, the PCI and the CRS, or the RSSI from thereceiver 101. The neighbor cell measurement section 135 performs thelayer 3 filtering for each cell having the PCI of the above frequency,and outputs the calculated RSRP or RSSI to the measurement manager 113together with the frequency and the PCI.

In order to perform radio link monitoring (Radio Link Monitoring: RLM),the RLM controller 115 outputs the measurement of the CRS to thereceiver 101. Upon receiving the measurement resource restriction forthe own cell, in order to monitor the radio link in the resourceinstructed in the input measurement resource restriction, the RLMcontroller 115 instructs the receiver 101 to measure the CRS in theabove resource. The RLM controller 115 monitors the radio link of theown cell on the basis of the configuration necessary for monitoring theCRS and the RLM which have been input from the receiver 101. If the RLMcontroller 115 determines that the RLF occurs, the RLM controller 115notifies the reconnection controller of the occurrence of the RLF.

Upon being notified of the occurrence of the RLF from the RLM controller115, the reconnection controller 117 instructs the RLF report generator119 to generate the RLF report. In order to perform the cell selection,the reconnection controller 117 instructs the receiver 101 to measurethe frequency and the CRS to be measured. The reconnection controller117 selects the cell to be connected on the basis of the value inputfrom the receiver 101. The reconnection controller 117 generates the RRCconnection reestablishment request message to be transmitted to theselected cell. Upon receiving the RRC connection reestablishment requestmessage, the reconnection controller 117 generates the RRC connectionreestablishment complete message. In this situation, upon receiving afact that the RLF information is available from the RLF report generator119, the reconnection controller 117 generates the RRC connectionreestablishment complete message in which the REF information availableflag is set to the true. The reconnection controller 117 instructs thetransmitter 105 to transmit the RRC connection reestablishment requestmessage or the RRC connection reestablishment complete message.

Upon receiving an instruction for generating the RLF report from thereconnection controller 117, the RLF report generator 119 instructs themeasurement manager 113 to output the held information. The RLF reportgenerator 119 generates the RLF report on the basis of the informationinput from the measurement manager 113. The RLF report includes the RSRPor the RSRQ of the own cell which has been measured without the use ofthe measurement resource restriction, the RSRP or the RSRQ of the owncell which has been measured with the use of the measurement resourcerestriction, or the RSRP or the RSRQ of the neighbor cell. With thisconfiguration, the measurement result when the measurement resourcerestriction is used can be compared with the measurement result when themeasurement resource restriction is not used. As a result, the gainobtained by using the measurement resource restriction can becalculated, and the network can be optimized.

When the value obtained by measuring the own cell with the use of themeasurement resource restriction is included, the RLF report generator119 may not include the value obtained by measuring the own cell withoutthe use of the measurement resource restriction. With the aboveconfiguration, because the state actually used by the terminal can begrasped by the base station, the network can be optimized. Also, ascompared with a case in which both of the measurement result of the owncell when the measurement resource restriction is not used, and themeasurement result of the own cell when the measurement resourcerestriction is used are included in the RLF report, the size of the RLFreport can be reduced.

When the RSRP or the RSRQ of the own cell which has been measured withthe use of the measurement resource restriction of the own cell isincluded in the RLF report, the RLF report generator 119 may set themeasurement resource restriction flag to the true (true). Themeasurement resource restriction flag may be configured by 1 bit. Withthe above configuration, because the base station can explicitly knowthat the measurement result is the value measured with the use of themeasurement resource restriction, the base station can easily know thatany state has been measured. When the base station can know whether themeasurement result is the value obtained by using the measurementresource restriction through the network, or not, by another method, themeasurement resource restriction flag is not included in the messageconfiguration. When the RLF report generator 119 generates the RLFreport, the RLF report generator 119 outputs that the RLF report hasbeen generated to the reconnection controller 117, and outputs the RLFreport to the RLF report manager 121.

When receiving an instruction for transmitting the RLF report to thebase station from the controller 103, the RLF report manager 121generates the terminal information response message including the RLFreport input from the RLF report generator 119. The RLF report manager121 instructs the transmitter 105 to transmit the terminal informationresponse message.

The transmitter 105 transmits the response message to the individualcontrol information, the RRC connection reestablishment request message,the RRC connection reestablishment complete message, or the terminalinformation response message including the RLF report.

[Configuration of Base Station According to First Embodiment]

FIG. 3 is a block diagram of the base station configuring the wirelesscommunication system according to the first embodiment. As illustratedin FIG. 3, the base station according to the first embodiment includes areceiver 151, a controller 153, and a transmitter 155. The controller153 includes a measurement configuration controller 161, a reconnectioncontroller 163, and an RLF controller 165.

The receiver 151 receives the response message to the individual controlinformation transmitted from the terminal, the RRC connectionreestablishment request message, the RRC connection reestablishmentcomplete message, or the terminal information response message, andoutputs the received message to the controller 153.

When the controller 153 determines that the terminal performs themeasurement of the own cell, and the RLM in the specific resource, thecontroller 153 generates the individual control information includingthe measurement resource restriction for the own cell. The controller153 generates the individual control information including themeasurement configuration input from the measurement configurationcontroller 161. The controller 153 instructs the transmitter 155 totransmit the individual control information. Upon receiving the RRCconnection reestablishment request message, the controller 153 outputsthe received message to the reconnection controller 163. If the RLFinformation available flag is included in the RRC connectionreestablishment complete message, and set to the true (true), thecontroller 153 outputs that the terminal holds the RLF information tothe RLF controller 165.

The measurement configuration controller 161 of the controller 153generates the measurement configuration (Measurement Configuration) forthe movement control. The measurement configuration includes ameasurement object (MeasObject), a report configuration (ReportConfig),a measurement Identifier (MeasID), a filtering parameter(Quantityconfig) of the measurement result report, a measurement gapindicative of a period during which data for measuring another frequencyor another system by the terminal is not transmitted or received, and athreshold value (S-measure) of the own cell requiring the measurementstart of the neighbor cell. The measurement configuration controller 161outputs the measurement configuration generated in the controller 153.Upon receiving the terminal information response message including theRLF report, the controller 153 outputs the RLF report to the RLFcontroller 165.

Upon receiving the RRC connection reestablishment request message, thereconnection controller 163 determines whether the connection of theterminal described in the above message can be reestablished, or not.When the reconnection controller 163 determines that the connection ofthe above terminal can be reestablished, the reconnection controller 163generates the RRC connection reestablishment message, and outputs thegenerated message to the transmitter 155.

Upon being notified that the terminal holds the RLF information, the RLFcontroller 165 determines whether the RLF information is collected, ornot. When the RLF controller 165 determines that the RLF information ofthe terminal is collected, the RLF controller 165 generates the terminalinformation request message (UEInformationRequest) in which the RLFreport request flag (rlf-ReportReq) is set to the true (true), andoutputs the generated message to the transmitter 155. Upon receiving theRLF report, the RLF controller 165 determines whether the measurementresult of the own cell included in the above report is the valuemeasured by the measurement resource restriction, or not. Thedetermination method may acquire the measurement configuration from thebase station to which the terminal has been connected at the time of theRLF, and perform the determination. Also, if the terminal includes themeasurement resource restriction flag, the terminal may perform thedetermination according to the flag. The RLF controller 165 optimizesthe network on the basis of the RLF report. The network may be optimizedby sharing the RLF report within the network.

The transmitter 155 transmits the individual control information, theRRC connection reestablishment message, or the terminal informationrequest message to the terminal.

Subsequently, the operation of the first embodiment will be described.FIG. 4 is a flowchart illustrating an example of the operation of theterminal according to the first embodiment.

The terminal determines whether the measurement resource restriction forthe own cell is included in the individual control information, or not(Step S101). If the measurement resource restriction for the own cell isnot included in the individual control information (no), the terminalallows the operation to proceed to Step S102. On the other hand, if themeasurement resource restriction for the own cell is included in theindividual control information (yes), the terminal allows the operationto proceed to Step S103.

In Step S102, the terminal performs the measurement of the own cellwithout the use of the measurement resource restriction. The terminalrepeats the measurement of the own cell in Step S102 as indicated by adotted line in the figure, while allowing the operation to proceed toStep S104. In Step S103, the terminal performs the measurement of theown cell with the use of the measurement resource restriction. Theterminal repeats the measurement of the own cell in Step S103 asindicated by a dotted line in the figure, while allowing the operationto proceed to Step S104.

In Step S104, the terminal performs the measurement of the neighbor cellaccording to the measurement configuration. The terminal repeats themeasurement of the neighbor cell in Step S104 as indicated by a dottedline in the figure, while allowing the operation to proceed to StepS105. When the terminal detects the RLF in Step S105, the above terminaldetermines whether the RLF report is available, or not (Step S106). Ifthe terminal determines that the RLF report is available (yes), theterminal allows the operation to proceed to Step S108. On the otherhand, if the terminal determines that the RLF information is notavailable (no), the terminal allows the operation to proceeds to StepS107.

In Step S107, the terminal performs the cell selection, andreestablishes the connection to a suitable cell. If the terminal cannotreestablish the connection to the suitable cell, the terminal becomes inthe idle state. In Step S108, the terminal performs the cell selection,and reestablishes the connection to the suitable cell. In thissituation, the terminal includes the RLF information available flag setto the true in the RRC connection reestablishment complete message, andtransmits the message, and allows the operation to proceeds to StepS109. If the terminal cannot reestablish the connection to the suitablecell, the terminal becomes in the idle state.

In Step S109, the terminal receives the terminal information requestmessage in which the RLF information request flag is set to the truefrom the base station, and allows the operation to proceed to Step S110.If the terminal does not receive the terminal information requestmessage in which the RLF information request flag is set to the truefrom the base station, the processing subsequent to Step S109 is notgenerated.

In Step S110, the terminal determines whether to hold the value measuredby the resource of the measurement resource restriction, or not. If theterminal holds the value measured by the resource of the measurementresource restriction (yes), the terminal allows the operation to proceedto Step S112. On the other hand, if the terminal does not hold the valuemeasured by the resource of the measurement resource restriction (not),the terminal allows the operation to proceed to Step S111.

In Step S111, the terminal generates the RLF report by the valuemeasured without the use of the measurement resource restriction, andallows the operation to proceeds to Step S113. In Step S112, theterminal generates the RLF report including the value measured with theuse of the measurement resource restriction, and allows the operation toproceed to Step S113. The terminal may include both of the valuemeasured with the use of the measurement resource restriction, and thevalue measured without the use of the measurement resource restrictionin the own cell. The terminal may include only the value measured withthe use of the measurement resource restriction in the own cell. Also,in order to report to the base station that the value has been measuredwith the use of the measurement resource restriction, the terminal maygenerate the RLF report in which the measurement resource restrictionflag is set to the true (true).

In Step S113, the terminal transmits the RLF report to the base station.

As described above, according to this embodiment, the terminal includesthe value of the own cell which has been measured with the use of themeasurement resource restriction in the RLF report. For that reason, thebase station that has received the RLF report can precisely grasp thestate of the own cell in which the RLF occurs in the terminal even underthe environment in which the ABS is used.

Second Embodiment

A wireless communication system according to a second embodiment will bedescribed with reference to FIGS. 5 to 8. The wireless communicationsystem according to this embodiment is different from that in the firstembodiment in that the value measured with the use of the measurementresource restriction as the measured value of the neighbor cell isincluded in the RLF report. The other configurations are identical withthose in the first embodiment, and in FIGS. 6 to 8, the commoncomponents or steps with those in the corresponding drawings in thefirst embodiment are denoted by the same reference symbols.

FIG. 5 is a timing chart when the terminal transmits the RLF report inthe wireless communication system according to the second embodiment. Asillustrated in FIG. 5, a base station (first base station) connectedwith the terminal transmits an RRC connection reconfiguration message(RRC Connection Reconfiguration) to the terminal. The RRC connectionreconfiguration message includes control information and a measurementconfiguration (Measurement Configuration: MC). The control informationincludes the measurement resource restrictions (Measurement ResourceRestriction) for measurement of the own cell and radio link monitoringif the occasion demands. Also, the measurement configuration includes alist of the neighbor cell that applies the measurement resourcerestriction and the measurement resource restriction if the occasiondemands. The measurement resource restriction is set for each of thefrequencies. The measurement resource restriction may have a pluralityof patterns at one frequency, and attach the neighbor cell list to therespective patterns. With this configuration, a measurement precision ofthe neighbor cell can be more finely enhanced.

Upon receiving the RRC connection reconfiguration message from the basestation, the terminal transmits an RRC connection reconfigurationcomplete message (RRC Connection Reconfiguration Complete) to the basestation. Also, the terminal performs the measurement (Measurement) andthe radio link monitoring on the basis of the control information andthe measurement configuration from the base station. Upon detecting theradio link failure (RLF), the terminal detects a suitable cell (SuitableCell) with the use of cell selecting means, and selects the cell. Then,the terminal transmits an RRC connection reestablishment request message(RRC Connection Reestablishment Request) to a base station (second basestation) selected by the cell selection.

Upon receiving the RRC connection reestablishment request message fromthe terminal, the base station determines whether to accept the RRCconnection reestablishment request of the terminal, or not. Upondetermining to accept the terminal, the base station transmits an RRCconnection reestablishment message (RRC Connection Reestablishment) tothe terminal. Upon receiving the RRC connection reestablishment message,the terminal generates the RRC connection reestablishment completemessage (RRC Connection Reestablishment Complete). If the RLFinformation related to the radio link failure (RLF) finally generated isavailable, the terminal includes an RLF information available flag(rlf-InfoAvailable) in the RRC connection reestablishment message, andsets the flag to the true (true). The terminal transmits the RRCconnection reestablishment complete message to the base station.

As described above, the terminal completes the RRC connectionreestablishment. On the other hand, the base station receives the RRCconnection reestablishment complete message in which the RLF informationavailable flag is set to the true (true) from the terminal. The basestation determines whether the information from the terminal at the timeof the radio link failure is necessary, or not. When the base stationdetermines that the information from the terminal is necessary the basestation transmits the terminal information request message(UEInformationRequest) in which an RLF report request flag(rlf-ReportReq) is set to the true (true) to the terminal in order torequest the terminal to transmit the information at the time of radiolink failure. The terminal receives the terminal information requestmessage in which the RLF report request flag is set to the true. If themeasurement resource restriction (Measurement Resource Restriction) formeasurement of the own cell is included in the control information, theterminal generates an RLF report (rlf-Report) including the valueobtained by measuring the own cell with the use of the measurementresource restriction. Also, if the measurement resource restriction isincluded in the measurement configuration, the terminal generates theRLF report (rlf-Report) including the value obtained by measuring theneighbor cell with the use of the measurement resource restriction. Theterminal generates a terminal information response message(UEInformationResponse) including the RLF report, and transmits thegenerated message to the base station.

The RLF report includes the value obtained by measuring the own cellwith the use of the measurement resource restriction in addition to thevalue obtained by measuring the own cell without use of the measurementresource restriction. Further, the RLF report includes the valueobtained by measuring the neighbor cell with the use of the measurementresource restriction, in addition to the value obtained by measuring theneighbor cell without the use of the measurement resource restriction.With this configuration, because the measurement result when themeasurement resource restriction is used can be compared with themeasurement result when the measurement resource restriction is notused, a gain obtained by using the measurement resource restriction canbe calculated, and the network can be optimized.

Also, when the value obtained by measuring the own cell with the use ofthe measurement resource restriction is included in the RLF report, thevalue obtained by measuring the own cell without use of the measurementresource restriction may not be included. Further, if the RLF reportincludes the value obtained by measuring the neighbor cell with the useof the measurement resource restriction, the RLF report may not includethe value measured without the use of the measurement resourcerestriction for the above neighbor cell. With this configuration,because the base station can grasp a state in which the terminal hasbeen actually used, the network can be optimized. Also, as compared witha case in which both of the measurement result of the own cell or theneighbor cell when the measurement resource restriction is not used, andthe measurement result of the own cell or the neighbor cell when themeasurement resource restriction is used are included in the RLF report,the size of the RLF report can be reduced.

When the value obtained by measuring the own cell or the neighbor cellwith the use of the measurement resource restriction is included in theRLF report, that the value is measured by using the measurement resourcerestriction may be notified with the use of the flag for each cell. Theflag may be configured by 1 bit. With this configuration, because thebase station can explicitly know that the measurement result is thevalue measured by using the measurement resource restriction, the basestation can easily know that any state has been measured. The RLF reportmay be generated in distinction between a group of the measurementresult measured with the use of the measurement resource restriction,and a group of the measurement result measured without the use of themeasurement resource restriction. With this configuration, because onlyone flag needs to be added as a while without need to add the flag foreach of the cells, the size of the message can be reduced. With theexchange of the measurement configuration information between the basestations, the base station may grasp whether the measurement result isthe value measured with the use of the measurement resource restriction,or not. With this configuration, the addition of the signaling in theradio resource can be suppressed.

The above description is exemplary, and the RLF report may betransmitted by a technique other than the above technique. For example,the terminal transitions to an idle state (Idle) after having detectedthe RLF. Thereafter, when the connection is newly established, the RLFinformation available flag (rlf-InfoAvailable) may be set to the true(true) and included in an RRC connection setup complete message (RRCConnection Setup Complete), and transmitted to the base station. Withthe above configuration, because the base station can know that theterminal holds the RLF report, the base station transmits the terminalinformation request message in which the RLF report request(rlf-Reportreq) is set to the true to the terminal, and can obtain theterminal information response message including the RLF report(rlf-report) from the terminal.

In the system described above, the first base station and the secondbase station may be configured by an identical base station. Also, adestination of the RLF report (rlf-report) from the terminal is notlimited to the second base station, but may be another base station withwhich the terminal can communicate.

[Configuration of Terminal According to Second Embodiment]

FIG. 6 is a block diagram of the terminal configuring the wirelesscommunication system according to the second embodiment. As illustratedin FIG. 6, the terminal according to the second embodiment includes areceiver 201, a controller 203, and a transmitter 105. The terminalaccording to this embodiment is different from the terminal according tothe first embodiment in the receiver 201 as well as a measurementconfiguration manager 211, a measurement manager 213, and an RLF reportgenerator 219 installed in the controller 203. Also, a neighbor cellmeasurement section 235 installed in a measurement manager 213 accordingto this embodiment is different from that of the first embodiment.Further, the measurement manager 213 according to this embodiment has arestricted neighbor cell measurement section 237.

The receiver 201 receives the CRS or the RSSI of the target cell in thespecific resource according to an instruction from the restrictedneighbor cell measurement section 237 installed in the measurementmanager 213 of the controller 203, in addition to the function of thereceiver 101 in the first embodiment. The receiver 201 outputs thereceived CRS or RSSI to the restricted neighbor cell measurement section237 together with the frequency and the PCI.

The measurement configuration manager 211 outputs the PCI of the owncell, the frequency of the own cell, and the configuration necessary formeasurement of the own cell to the own cell measurement section 131.When the measurement resource restriction (Measurement ResourceRestriction) for the own cell is input to the measurement configurationmanager 211, the measurement configuration manager 211 outputs themeasurement resource restriction for the own cell, the PCI of the owncell, the frequency of the own cell, and the information necessary formeasurement of the own cell to the restricted own cell measurementsection 133.

When the measurement resource restriction is included in the measurementconfiguration, the measurement configuration manager 211 outputs thetarget frequency of the measurement resource restriction, the neighborcell list, and the target measurement configuration included in themeasurement configuration to the restricted neighbor cell measurementsection 237. On the other hand, when the neighbor cell list is not setin the measurement resource restriction, the measurement configurationmanager 211 applies the measurement resource restriction to all of theneighbor cells of that frequency. The measurement configuration manager211 outputs the configuration necessary for measurement of the neighborcell included in the measurement configuration to the neighbor cellmeasurement section 235. If only the value measured with the use of themeasurement resource restriction is included in the RLF report as themeasured value of the neighbor cell, the measurement configurationmanager 211 may output the configuration to the neighbor cellmeasurement section 235 so as not to measure the target neighbor cell ofthe measurement resource restriction.

The measurement manager 213 manages the RSRP and the RSRQ of the owncell in distinction between the RSRP and the RSRQ measured without theuse of the measurement resource restriction, and the RSRP and the RSRQmeasured with the use of the measurement resource restriction. Themeasurement manager 213 calculates the RSRQ according to the RSRP andthe received signal strength indication (Received Signal StrengthIndication: RSSI) which have been input from the own cell measurementsection 131, and manages the RSRP and the RSRQ as the RSRP and the RSRQof the own cell which have been measured without the use of themeasurement resource restriction. The measurement manager 213 calculatesthe RSRQ according to the RSRP and the RSSI which have been input fromthe restricted own cell measurement section 133, and manages the RSRPand the RSRQ as the RSRP and the RSRQ of the own cell which have beenmeasured with the use of the measurement resource restriction.

The measurement manager 213 manages the RSRP and the RSRQ of theneighbor cell for each PCI and each frequency. When the measurementmanager 213 determines that the measurement of the neighbor cell isnecessary, according to the managed value and measurement configuration,the measurement manager 213 instructs the neighbor cell measurementsection 235 to measure the neighbor cell. The measurement manager 213manages the RSRP and the RSRQ of the neighbor cell in distinctionbetween the RSRP and the RSRQ measured without the use of themeasurement resource restriction, and the RSRP and the RSRQ measuredwith the use of the measurement resource restriction. The measurementmanager 213 calculates the RSRQ of the cell having the PCI of the abovefrequency according to the RSRP, the RSSI, the PCI, and the frequencywhich have been input from the neighbor cell measurement section 235,and manages the RSRP and the RSRQ as the RSRP and the RSRQ measuredwithout the use of the measurement resource restriction of the cellhaving the PCI of the above frequency. In the same frequency, a commonvalue may be used in the RSSI of the own cell and the neighbor cell,which has been measured without the use of the measurement resourcerestriction.

In the RSSI of the own cell, a common value may be used between the RSSIof the own cell measured without being restricted to the specificresource, and the RSSI of the own cell measured with the use of themeasurement resource restriction. The measurement manager 213 calculatesthe RSRQ of the cell having the PCI of the above frequency according tothe RSRP, the RSSI, the PCI, and the frequency which have been inputfrom the restricted neighbor cell measurement section 237, and managesthe RSRP and the RSRQ as the RSRP and the RSRQ measured with the use ofthe measurement resource restriction of the cell having the PCI of theabove frequency. Upon receiving an instruction for outputting the heldinformation from the RLF report generator 219, the measurement manager213 outputs the held RSRP and the RSQR of the respective cells to theRLF report generator 219. In this situation, if the RSRP or the RSRQwhich has been measured with the use of the measurement resourcerestriction is present in the own cell or the neighbor cell, themeasurement manager 213 also outputs the above information to the RLFreport generator 219. However, because the measurement of the RSRQ isnot essential, the own cell measurement section 131, the restricted owncell measurement section 133, the neighbor cell measurement section 235,and the restricted neighbor cell measurement section 237 may not inputthe RSSI to the measurement manager 213. Therefore, the measurementmanager 213 may output only the RSRP of a part or all of the cells,which is output to the RLF report generator 219, to the RLF reportgenerator 219.

The neighbor cell measurement section 235 may have a function that doesnot perform the measurement of the neighbor cell instructed not to bemeasured from the measurement manager 213, in addition to the functionof the neighbor cell measurement section 135 according to the firstembodiment.

The restricted neighbor cell measurement section 237 measures the RSRPor the RSSI of all the cells of the above frequency if the cell includedin the input neighbor cell list or the neighbor cell list is not input,with the use of the measurement resource restriction in the targetfrequency of the measurement resource restriction input from themeasurement configuration manager 211. Therefore, the restrictedneighbor cell measurement section 237 instructs the receiver 201 tomeasure the CRS or the RSSI of the own cell in the resource instructedwith the measurement resource restriction. The restricted neighbor cellmeasurement section 237 performs the layer 3 filtering on the CRS or theRSSI input from the receiver 201, and outputs the calculated RSRP orRSSI to the measurement manager 213 together with the frequency and thePCI.

Upon receiving an instruction for generating the RLF report from thereconnection controller 117, the RLF report generator 219 instructs themeasurement manager 213 to output the held information. The RLF reportgenerator 219 generates the RLF report on the basis of the informationinput from the measurement manager 213. The RLF report includes the RSRPor the RSRQ of the own cell which has been measured without the use ofthe measurement resource restriction of the own cell, the RSRP or theRSRQ of the own cell which has been measured with the use of themeasurement resource restriction of the own cell, the RSRP or the RSRQof the neighbor cell which has been measured without the use of themeasurement resource restriction, or the RSRP or the RSRQ of theneighbor cell which has been measured with the use of the measurementresource restriction. With this configuration, the measurement resultwhen the measurement resource restriction is used can be compared withthe measurement result when the measurement resource restriction is notused. As a result, the gain obtained by using the measurement resourcerestriction can be calculated, and the network can be optimized.

When the value obtained by measuring the own cell with the use of themeasurement resource restriction is included, the RLF report generator219 may not include the value obtained by measuring the own cell withoutthe use of the measurement resource restriction. Further, when the valueobtained by measuring the neighbor cell with the use of the measurementresource restriction is included, the RLF report generator 219 may notinclude the value obtained by measuring the neighbor cell without theuse of the measurement resource restriction. With the aboveconfiguration, because the state in which the terminal has been actuallyused can be grasped by the base station, the network can be optimized.Also, as compared with a case in which both of the measurement result ofthe own cell or the neighbor cell when the measurement resourcerestriction is not used, and the measurement result of the own cell orthe neighbor cell when the measurement resource restriction is used areincluded in the RLF report, the size of the RLF report can be reduced.

When the RSRP or the RSRQ which has been measured with the use of themeasurement resource restriction is included in the RLF report, the RLFreport generator 219 may set the measurement resource restriction flagto the true (true) for each of the cells. The measurement resourcerestriction flag may be configured by 1 bit. With the aboveconfiguration, because the base station can explicitly know that themeasurement result is the value measured with the use of the measurementresource restriction, the base station can easily know that any statehas been measured. The RLF report generator 219 may generate the RLFreport in distinction between a group of the measurement result measuredwith the use of the measurement resource restriction, and a group of themeasurement result measured without the use of the measurement resourcerestriction. With this configuration, because only one flag needs to beadded as a while without need to add the flag for each of the cells, thesize of the message can be reduced. When the base station can knowwhether the measurement result is the value obtained by using themeasurement resource restriction through the network, or not, by anothermethod, the measurement resource restriction flag is not included in themessage configuration. When the RLF report generator 219 generates theRLF report, the RLF report generator 219 outputs that the RLF report hasbeen generated to the reconnection controller 117, and outputs the RLFreport to the RLF report manager 121.

[Configuration of Base Station According to Second Embodiment]

FIG. 7 is a block diagram of the base station configuring the wirelesscommunication system according to the second embodiment. As illustratedin FIG. 7, the base station according to the second embodiment includesthe receiver 151, a controller 253, and the transmitter 155. The basestation according to this embodiment is different from the base stationaccording to the first embodiment in a measurement configurationcontroller 261 and an RLF controller 265 provided in the controller 253.

The measurement configuration controller 261 of the controller 253 has afunction of including the measurement resource restriction in themeasurement configuration in addition to the function of the measurementconfiguration controller 161 according to the first embodiment. Themeasurement resource restriction configures the neighbor cell list to besubjected to the measurement resource restriction, which is included inthe measurement target together. When all of the cells to be measuredare measured by the measurement resource restriction, the neighbor celllist is not included. The measurement resource restriction may beincluded in not the measurement target, but the report configuration, ormay be associated with the measurement identifier. Further, themeasurement resource restriction may have a plurality of patterns at noteach frequency but one frequency, and attach the neighbor cell list tothe respective patterns.

In addition to the function of the RLF controller 165 according to thefirst embodiment, the RLF controller 265 has a function of determiningwhether the measurement result of the neighbor cell included in theabove report is the measurement resource restriction, or not, uponreceiving the RLF report. The determination method may acquire themeasurement configuration from base station to which the terminal hasbeen connected at the time of the RLF for determination, may perform thedetermination by the flag if the terminal includes the measurementresource restriction flag for each of the cells, or may perform thedetermination by groups if the values measured with the use of themeasurement resource restriction and the values measured without the useof the measurement resource restriction are classified into the groups.

Subsequently, the operation of the terminal according to the secondembodiment will be described. FIG. 8 is a flowchart illustrating anexample of the operation of the terminal according to the secondembodiment. In the flowchart illustrated in FIG. 8, Steps S201 to S203are performed instead of Step S104 in the flowchart according to thefirst embodiment illustrated in FIG. 4, and Step S204 is performedinstead of Step S112.

In Step S102, the measurement of the own cell is performed without usingthe measurement resource restriction. The terminal repeats themeasurement of the own cell in Step S102 as indicated by a dotted linein the figure, while allowing the operation to proceed to Step S201. InStep S103, the terminal performs the measurement of the own cell withthe use of the measurement resource restriction. The terminal repeatsthe measurement of the own cell in Step S103 as indicated by a dottedline in the figure, while allowing the operation to proceed to StepS201.

In Step S201, the terminal determines whether the measurement resourcerestriction for the neighbor cell is included in the measurementconfiguration, or not. If the measurement resource restriction for theneighbor cell is not included in the measurement configuration (no), theoperation proceeds to Step S202. On the other hand, if the measurementresource restriction for the neighbor cell is included in themeasurement configuration (yes), the operation proceeds to Step S203.

In Step S202, the terminal performs the measurement of the neighbor cellwithout the use of the measurement resource restriction. The terminalrepeats the measurement of the neighbor cell in Step S202 as indicatedby a dotted line in the figure, while allowing the operation to proceedto Step S105. In Step S203, the terminal performs the measurement of thecell included in the neighbor cell list with the use of the measurementresource restriction. If the neighbor cell list is not included, theterminal measures all of the cells of the frequency in which themeasurement resource restriction is configured with the use of themeasurement resource restriction. The terminal repeats the measurementof the neighbor cell in Step S203 as indicated by a dotted line in thefigure, while allowing the operation to proceed to Step S105.

In Step S110, if the terminal determines to hold the value measured bythe resource of the measurement resource restriction (yes), the terminalallows the operation to proceed to Step S204.

In Step S204, the terminal generates the RLF report with the inclusionof the value measured with the use of the measurement resourcerestriction, and allows the operation to proceeds to Step S113. Theterminal may include both of the value measured with the use of themeasurement resource restriction, and the value measured without the useof the measurement resource restriction for the own cell or the neighborcell. If the terminal includes the value measured with the use of themeasurement resource restriction for the own cell or the neighbor cell,the terminal may not include the value measured without the use of themeasurement resource restriction. Also, in order to report to the basestation that the value has been measured with the use of the measurementresource restriction, the terminal may generate the RLF report in whichthe measurement resource restriction flag is included for each of thecells, and set to the true (true). The measurement resource restrictionflag may be configured by 1 bit.

As described above, according to this embodiment, the terminal includesthe value of the own cell and the value of the neighbor cell, which havebeen measured with the use of the measurement resource restriction inthe RLF report. For that reason, the base station that has received theRLF report can precisely grasp the states of the own cell and theneighbor cell in which the RLF occurs in the terminal even under theenvironment in which the ABS is used.

Third Embodiment

A wireless communication system according to a third embodiment will bedescribed with reference to FIGS. 9 to 11. The wireless communicationsystem according to this embodiment is different from that in the firstembodiment in that the value measured with the use of the measurementresource restriction as the measured value of the neighbor cell isincluded in the RLF report. Therefore, in the wireless communicationsystem according to the third embodiment, the operation of parts of thecomponents of the terminal is different from that in the firstembodiment. The other configurations are identical with those in thefirst embodiment, and in FIGS. 10 to 11, the common components or stepswith those in the corresponding drawings in the first embodiment aredenoted by the same reference symbols.

FIG. 9 is a timing chart when the terminal transmits the RLF report inthe wireless communication system according to the third embodiment. Asillustrated in FIG. 9, a base station (first base station) connectedwith the terminal transmits an RRC connection reconfiguration message(RRC Connection Reconfiguration) to the terminal. The RRC connectionreconfiguration message includes control information and a measurementconfiguration (Measurement Configuration: MC). The control informationincludes the measurement resource restrictions (Measurement ResourceRestriction) for measurement of the own cell and radio link monitoringif the occasion demands.

Upon receiving the RRC connection reconfiguration message from the basestation, the terminal transmits an RRC connection reconfigurationcomplete message (RRC Connection Reconfiguration Complete) to the basestation. Also, the terminal performs the measurement (Measurement) andthe radio link monitoring on the basis of the control information andthe measurement configuration from the base station. If the measurementresource restriction for the own cell is included in the controlinformation, the terminal measures the neighbor cells of the samefrequency with the use of the measurement resource restriction. Upondetecting the radio link failure (RLF), the terminal detects a suitablecell (Suitable Cell) with the use of cell selecting means, and selectsthe detected cell. Then, the terminal transmits an RRC connectionreestablishment request message (RRC Connection Reestablishment Request)to a base station (second base station) selected by the cell selection.

Upon receiving the RRC connection reestablishment request message fromthe terminal, the base station determines whether to accept the RRCconnection reestablishment request of the terminal, or not. Upondetermining to accept the terminal, the base station transmits an RRCconnection reestablishment message (RRC Connection Reestablishment) tothe terminal. Upon receiving the RRC connection reestablishment message,the terminal generates the RRC connection reestablishment completemessage (RRC Connection Reestablishment Complete). If the RLFinformation related to the radio link failure (RLF) finally generated isavailable, the terminal includes an RLF information available flag(rlf-InfoAvailable) in the RRC connection reestablishment message, andsets the flag to the true (true). The terminal transmits the RRCconnection reestablishment complete message to the base station.

As described above, the terminal completes the RRC connectionreestablishment. On the other hand, the base station receives the RRCconnection reestablishment complete message in which the RLF informationavailable flag is set to the true (true) from the terminal. The basestation determines whether the information from the terminal at the timeof the radio link failure is necessary, or not. When the base stationdetermines that the information from the terminal is necessary the basestation transmits the terminal information request message(UEInformationRequest) in which an RLF report request flag(rlf-ReportReq) is set to the true (true) to the terminal in order torequest the terminal to transmit the information at the time of radiolink failure. The terminal receives the terminal information requestmessage in which the RLF report request flag is set to the true. If themeasurement resource restriction (Measurement Resource Restriction) formeasurement of the own cell is included in the control information, theterminal generates an RLF report (rlf-Report) including the valueobtained by measuring the own cell with the use of the measurementresource restriction, and the value of the neighbor cell of the samefrequency measured with the use of the measurement resource restriction.The terminal generates a terminal information response message(UEInformationResponse) including the RLF report, and transmits thegenerated message to the base station. With the above configuration,because the neighbor cell is measured at a timing when measuring the owncell, the state of the neighbor cell at the timing when measuring theown cell can be grasped. Therefore, the state in which the RLF occurscan be more grasped.

The RLF report includes the value obtained by measuring the own cellwith the use of the measurement resource restriction in addition to thevalue obtained by measuring the own cell without use of the measurementresource restriction. Further, the RLF report includes the valueobtained by measuring the neighbor cell with the use of the measurementresource restriction, in addition to the value obtained by measuring theneighbor cell without the use of the measurement resource restriction.With this configuration, because the measurement result when themeasurement resource restriction is used can be compared with themeasurement result when the measurement resource restriction is notused, a gain obtained by using the measurement resource restriction canbe calculated, and the network can be optimized.

Also, when the value obtained by measuring the own cell with the use ofthe measurement resource restriction is included in the RLF report, thevalue obtained by measuring the own cell without use of the measurementresource restriction may not be included. Further, if the RLF reportincludes the value obtained by measuring the neighbor cell with the useof the measurement resource restriction, the RLF report may not includethe value measured without the use of the measurement resourcerestriction for the above neighbor cell. With this configuration,because the base station can grasp a state in which the terminal hasbeen actually used, the network can be optimized. Also, as compared witha case in which both of the measurement result of the own cell or theneighbor cell when the measurement resource restriction is not used, andthe measurement result of the own cell or the neighbor cell when themeasurement resource restriction is used are included in the RLF report,the size of the RLF report can be reduced.

When the value obtained by measuring the own cell or the neighbor cellwith the use of the measurement resource restriction is included in theRLF report, that the value is measured by using the measurement resourcerestriction may be notified with the use of the flag for each cell. Theflag may be configured by 1 bit. With this configuration, because thebase station can explicitly know that the measurement result is thevalue measured by using the measurement resource restriction, the basestation can easily know that any state has been measured. The RLF reportmay be generated in distinction between a group of the measurementresult measured with the use of the measurement resource restriction,and a group of the measurement result measured without the use of themeasurement resource restriction. With this configuration, because onlyone flag needs to be added as a while without need to add the flag foreach of the cells, the size of the message can be reduced. With theexchange of the measurement configuration information between the basestations, the base station may grasp whether the measurement result isthe value measured with the use of the measurement resource restriction,or not. With this configuration, the addition of the signaling in theradio resource can be suppressed.

The above description is exemplary, and the RLF report may betransmitted by a technique other than the above technique. For example,the terminal transitions to an idle state (Idle) after having detectedthe RLF. Thereafter, when the connection is newly established, the RLFinformation available flag (rlf-InfoAvailable) may be set to the true(true) and included in an RRC connection setup complete message (RRCConnection Setup Complete), and transmitted to the base station. Withthe above configuration, because the base station can know that theterminal holds the RLF report, the base station transmits the terminalinformation request message in which the RLF report request(rlf-Reportreq) is set to the true to the terminal, and can obtain theterminal information response message including the RLF report(rlf-report) from the terminal.

In the system described above, the first base station and the secondbase station may be configured by an identical base station. Also, adestination of the RLF report (rlf-report) from the terminal is notlimited to the second base station, but may be another base station withwhich the terminal can communicate.

[Configuration of Terminal According to Third Embodiment]

FIG. 10 is a block diagram of the terminal configuring the wirelesscommunication system according to the third embodiment. As illustratedin FIG. 10, the terminal according to the third embodiment includes areceiver 301, a controller 303, and a transmitter 105. The terminalaccording to this embodiment is different from the terminal according tothe first embodiment in the receiver 301 as well as a measurementconfiguration manager 311, a measurement manager 313, and an RLF reportgenerator 319 installed in the controller 303. Also, a neighbor cellmeasurement section 335 installed in a measurement manager 313 accordingto this embodiment is different from that of the first embodiment.Further, the measurement manager 313 according to this embodiment has arestricted neighbor cell measurement section 337.

The receiver 301 receives the CRS or the RSSI of the neighbor cellhaving the same frequency as that of the own cell in the specificresource according to an instruction from the restricted neighbor cellmeasurement section 337 installed in the measurement manager 313 of thecontroller 303, in addition to the function of the receiver 101 in thefirst embodiment. The receiver 301 outputs the received CRS or RSSI tothe restricted neighbor cell measurement section 337 together with thefrequency and the PCI.

The measurement configuration manager 311 has a function of outputtingthe configuration related to the frequency of the measurement resourcerestriction to the restricted neighbor cell measurement section 337among the configurations necessary for measurement of the neighbor cellincluded in the measurement configuration when the measurement resourcerestriction for the own cell is input, in addition to the function ofthe measurement configuration manager 1 in the first embodiment.

The measurement manager 313 manages the RSRP and the RSRQ of the owncell in distinction between the RSRP and the RSRQ measured without theuse of the measurement resource restriction, and the RSRP and the RSRQmeasured with the use of the measurement resource restriction. Themeasurement manager 313 calculates the RSRQ according to the RSRP andthe received signal strength indication (Received Signal StrengthIndication: RSSI) which have been input from the own cell measurementsection 131, and manages the RSRP and the RSRQ as the RSRP and the RSRQof the own cell which have been measured without the use of themeasurement resource restriction. The measurement manager 313 calculatesthe RSRQ according to the RSRP and the RSSI which have been input fromthe restricted own cell measurement section 133, and manages the RSRPand the RSRQ as the RSRP and the RSRQ of the own cell which have beenmeasured with the use of the measurement resource restriction.

The measurement manager 313 manages the RSRP and the RSRQ of theneighbor cell for each PCI of the neighbor cells, and each frequency.When the measurement manager 313 determines that the measurement of theneighbor cell is necessary, according to the managed value andmeasurement configuration, the measurement manager 313 instructs theneighbor cell measurement section 335 to measure the neighbor cell. Themeasurement manager 313 manages the RSRP and the RSRQ of the neighborcell in distinction between the RSRP and the RSRQ measured without theuse of the measurement resource restriction for the own cell, and theRSRP and the RSRQ measured with the use of the measurement resourcerestriction for the own cell. The measurement manager 313 calculates theRSRQ of the cell having the PCI of the above frequency according to theRSRP, the RSSI, the PCI, and the frequency which have been input fromthe neighbor cell measurement section 335, and manages the RSRP and theRSRQ as the RSRP and the RSRQ measured without the use of themeasurement resource restriction for the own cell of the cell having thePCI of the above frequency. In the same frequency, a common value may beused in the RSSI of the own cell and the neighbor cell, which has beenmeasured without the use of the measurement resource restriction. In theRSSI of the own cell, a common value may be used between the RSSI of theown cell measured without being restricted to the specific resource, andthe RSSI of the own cell measured with the use of the measurementresource restriction.

The measurement manager 313 calculates the RSRQ of the cell having thePCI of the above frequency according to the RSRP, the RSSI, the PCI, andthe frequency which have been input from the restricted neighbor cellmeasurement section 337, and manages the RSRP and the RSRQ as the RSRPand the RSRQ measured with the use of the measurement resourcerestriction for the own cell of the cell having the PCI of the abovefrequency. Upon receiving an instruction for outputting the heldinformation from the RLF report generator 319, the measurement manager313 outputs the held RSRP and the RSQR of the respective cells to theRLF report generator 319. In this situation, if the RSRP or the RSRQwhich has been measured with the use of the measurement resourcerestriction is present in the own cell or the neighbor cell, themeasurement manager 313 also outputs the above information to the RLFreport generator 319. However, because the measurement of the RSRQ isnot essential, the own cell measurement section 131, the restricted owncell measurement section 133, the neighbor cell measurement section 335,and the restricted neighbor cell measurement section 337 may not inputthe RSSI to the measurement manager 313. Therefore, the measurementmanager 313 may output only the RSRP of a part or all of the cells,which is output to the RLF report generator 319, to the RLF reportgenerator 319.

The neighbor cell measurement section 335 may have a function that doesnot perform the measurement of the same frequency as that of the owncell, in addition to the function of the neighbor cell measurementsection 135 according to the first embodiment.

In order to measure the RSRP and the RSSI of the neighbor cell with theuse of the measurement resource restriction in the frequency to besubjected to the measurement resource restriction input from themeasurement configuration manager 311, the restricted neighbor cellmeasurement section 337 instructs the receiver 301 to measure the CRS orthe RSSI in the resource instructed by the measurement resourcerestriction. The restricted neighbor cell measurement section 337subjects the CRS or RSSI input from the receiver 301 to the layer 3filtering, and outputs the calculated RSRP or RSSI to the measurementmanager 313 together with the frequency and the PCI.

Upon receiving an instruction for generating the RLF report from thereconnection controller 117, the RLF report generator 319 instructs themeasurement manager 313 to output the held information. The RLF reportgenerator 319 generates the RLF report on the basis of the informationinput from the measurement manager 313. The RLF report includes the RSRPor the RSRQ of the own cell or the neighbor cell which has been measuredwithout the use of the measurement resource restriction of the own cell,or the RSRP or the RSRQ of the own cell or the neighbor cell which hasbeen measured with the use of the measurement resource restriction ofthe own cell. With this configuration, the measurement result when themeasurement resource restriction for the own cell is used can becompared with the measurement result when the measurement resourcerestriction for the own cell is not used. As a result, the gain obtainedby using the measurement resource restriction for the own cell can becalculated, and the network can be optimized.

When the value obtained by measuring the own cell or the neighbor cellwith the use of the measurement resource restriction for the own cell isincluded, the RLF report generator 319 may not include the value of theown cell or the neighbor cell which has been measured without the use ofthe measurement resource restriction for the own cell. Further, when thevalue obtained by measuring the neighbor cell with the use of themeasurement resource restriction for the own cell is included, the RLFreport generator 319 may not include the value obtained by measuring theneighbor cell without the use of the measurement resource restrictionfor the own cell. With the above configuration, because the state inwhich the terminal has been actually used can be grasped by the basestation, the network can be optimized. Also, as compared with a case inwhich both of the measurement result of the own cell or the neighborcell when the measurement resource restriction for the own cell is notused, and the measurement result of the own cell or the neighbor cellwhen the measurement resource restriction for the own cell is used areincluded in the RLF report, the size of the RLF report can be reduced.

When the RSRP or the RSRQ which has been measured with the use of themeasurement resource restriction for the own cell is included in the RLFreport, the RLF report generator 319 may set the measurement resourcerestriction flag to the true (true) for each of the cells. With theabove configuration, because the base station can explicitly know thatthe measurement result is the value measured with the use of themeasurement resource restriction for the own cell, the base station caneasily know that any state has been measured. The RLF report generator319 may generate the RLF report in distinction between a group of themeasurement result measured with the use of the measurement resourcerestriction for the own cell, and a group of the measurement resultmeasured without the use of the measurement resource restriction for theown cell. With this configuration, because only one flag needs to beadded as a while without need to add the flag for each of the cells, thesize of the message can be reduced. When the base station can knowwhether the measurement result is the value obtained by using themeasurement resource restriction through the network, or not, by anothermethod, the measurement resource restriction flag is not included in themessage configuration. When the RLF report generator 319 generates theRLF report, the RLF report generator 319 outputs that the RLF report hasbeen generated to the reconnection controller 117, and outputs the RLFreport to the RLF report manager 121.

Subsequently, the operation of the terminal according to the thirdembodiment will be described. FIG. 11 is a flowchart illustrating anexample of the operation of the terminal according to the thirdembodiment. In the flowchart illustrated in FIG. 11, Steps S301 to S303are performed instead of Step S104 in the flowchart according to thefirst embodiment illustrated in FIG. 4, and Step S303 is performedinstead of Step S112.

In Step S102, the measurement of the own cell is performed without usingthe measurement resource restriction. The terminal repeats themeasurement of the own cell in Step S102 as indicated by a dotted linein the figure, while allowing the operation to proceed to Step S301. InStep S103, the terminal performs the measurement of the own cell withthe use of the measurement resource restriction. The terminal repeatsthe measurement of the own cell in Step S103 as indicated by a dottedline in the figure, while allowing the operation to proceed to StepS302.

In Step S301, the terminal performs the measurement of the neighbor cellwithout the use of the measurement resource restriction for the own cellaccording to the measurement configuration. The terminal repeats themeasurement of the neighbor cell in Step S301 as indicated by a dottedline in the figure, while allowing the operation to proceed to StepS105.

In Step S302, the terminal performs the measurement of the neighbor cellhaving the same frequency as that of the own cell with the use of themeasurement resource restriction for the own cell according to themeasurement configuration. In this step, in the neighbor cell of thefrequency different from that of the own cell, the terminal measures theneighbor cell according to the measurement configuration without the useof the measurement resource restriction for the own cell. The terminalrepeats the measurement of the neighbor cell in Step S302 as indicatedby a dotted line in the figure while allowing the operation to proceedto Step S105.

In Step S110, if the terminal determines to hold the value measured bythe resource of the measurement resource restriction (yes), the terminalallows the operation to proceed to Step S303.

In Step S303, the terminal generates the RLF report with the inclusionof the value measured with the use of the measurement resourcerestriction for the own cell, and allows the operation to proceeds toStep S113. The terminal may include both of the value measured with theuse of the measurement resource restriction, and the value measuredwithout the use of the measurement resource restriction for the own cellor the neighbor cell. If the terminal includes the value measured withthe use of the measurement resource restriction for the own cell or theneighbor cell, the terminal may not include the value measured withoutthe use of the measurement resource restriction of the neighbor cell.Also, in order to report to the base station that the value has beenmeasured with the use of the measurement resource restriction, theterminal may generate the RLF report in which the measurement resourcerestriction flag is included for each of the cells, and set to the true(true). The measurement resource restriction flag may be configured by 1bit.

As described above, according to this embodiment, the terminal includesthe values of the own cell and the neighbor cell, which have beenmeasured with the use of the measurement resource restriction for theown cell in the RLF report. For that reason, the base station that hasreceived the RLF report can grasp the state of the neighbor cell in theabove terminal at timing when the terminal measures the own cell, andtherefore can more precisely grasp the state under the ABS environment.

Fourth Embodiment

As described above, a precision in the measurement is different betweena value measured in a subframe of the ABS and a value measured in thesubframe which is not the ABS under the circumstance where the ABS isused. For that reason, in the conventional MDT (Minimization DriveTest), the precision with which the base station grasps the state of theterminal may be degraded. An object of the present invention accordingto the fourth embodiment of the present invention is to provide awireless communication terminal, a wireless communication base station,a wireless communication system, and a reporting method, in which anexternal device can precisely grasp the state of the respective cells inthe wireless communication terminal even under the environment where theABS is used.

The wireless communication system according to the fourth embodimentwill be described with reference to FIGS. 16 to 20. The wirelesscommunication system according to the fourth embodiment includes theterminal and the base station described before the description of thefirst embodiment. The terminal has a function of receiving a referencesignal transmitted from the base station in downlink for each of thecells, logging the measurement result derived on the basis of a givencalculation expression, and transmitting the logged measurement resultto the base station. Each base station performs the allocation andmanagement of the radio resources (for example, frequency band in afrequency domain or a time domain) to the respective terminals. Further,the base station has a function of an access point of the wirelessaccess network for the terminal.

FIG. 16 is a timing chart when a terminal transmits a logged measurementreport (LogMeasReport) in the wireless communication system according tothe fourth embodiment. As illustrated in FIG. 16, the base station(first base station) connected with the terminal transmits a loggedmeasurement configuration (Logged Measurement Configuration) to theterminal. The logged measurement configuration includes configurationinformation for logging the measurement result when the terminal is inan idle state. The logged measurement configuration includes,specifically, a present time (absoluteTimeInfo), a logging duration(loggingDuration), a logging interval (loggingInterval), a tracereference (traceReference), a trace recording session(traceRecordingSession), and a target area configuration(AreaConfiguration).

The terminal transitions to the idle state, and then performs the cellselection. The terminal starts to log the measurement result on thebasis of the logged measurement configuration of the selected cell. Whensystem information (System Information) received from a cell comingunder the control of the second base station includes the measurementresource restriction (Measurement Resource Restriction) for the owncell, the terminal measures the own cell on the basis of the measurementresource restriction. Then, the terminal logs the measurement result onthe basis of the logged measurement configuration. In this situation,the terminal logs that the measurement result has been measured on thebasis of the measurement resource restriction together. Also, theterminal performs cell reselection (Cell Reselection) to be connected,on the basis of the measurement results of the own cell and the neighborcell.

Upon reselecting the cell coming under the control of the third basestation, the terminal receives the system information (SystemInformation) from the cell. If the system information includes themeasurement resource restriction for the own cell, the terminal measuresthe own cell on the basis of the measurement resource restriction. Then,the terminal logs the measurement result on the basis of the loggedmeasurement configuration. The terminal logs that the measurement resulthas been measured on the basis of the measurement resource restrictiontogether. If the measurement resource restriction is not included, theterminal performs a normal measurement. Then, the terminal logs themeasurement result on the basis of the logged measurement configuration.

When the terminal transitions to a connected state, the terminaltransmits the RRC connection request (RRC Connection Request) message tothe third base station. Then, the third base station transmits an RRCconnection setup (RRC Connection Setup) message to the terminal. Whenthe terminal receives the RRC connection setup message, and completes asetup, the terminal transmits the RRC connection setup complete (RRCConnection Setup Complete) message. In this situation, if the terminalholds the logged measurement result based on the logged measurementconfiguration, the terminal transmits the RRC connection setup completemessage in which a logged measurement available (logMeasAvailable) flagis set to the true (true).

When the third base station receives the RRC connection setup completemessage in which the logged measurement available flag is set to thetrue, and determines that the logged measurement result is necessary,the third base station transmits the terminal information request (UEInformation Request) message to the terminal. The third base stationsets the logged measurement request (logMeasReportReq) flag of theterminal information request (UE Information Request) message to thetrue (true), and transmits the message to the terminal. When theterminal receives the terminal information request message in which thelogged measurement request flag is set to the true, the terminalincludes the held logged measurement result in the terminal informationresponse (UE Information Response) message, and transmits the message tothe third base station. The logged measurement result included in theterminal information response is “logged measurement report”. In thissituation, the terminal sets a flag (measurement resource restrictionflag) indicative of whether the logged measurement result is the valuemeasured on the basis of the measurement resource restriction, or not,for each of the cells. If the logged measurement result is the valuemeasured on the basis of the measurement resource restriction, theterminal sets the measurement resource restriction flag to the true(true). On the other hand, if the logged measurement result is the valuenot measured on the basis of the measurement resource restriction, theterminal does not set the measurement resource restriction flag.

With the above operation, the base station can determine whether thelogged measurement result received from the terminal is the valuemeasured on the basis of the measurement resource restriction, or not.For that reason, according to this embodiment, the state of the cell canbe more precisely grasped than the conventional art.

The terminal may start to log the measurement result since the terminaltransitions to the idle state.

The above description is exemplary and the terminal may notify the basestation that the logged measurement result is available through a methodother than the above method. For example, the terminal may set thelogged measurement available flag of the RRC connection reconfiguration(RRC Connection Reconfiguration complete) message at the time of thehandover to the true (true), and transmits the message. Also, theterminal may set the logged measurement available flag of the RRCconnection reestablishment Complete (RRC Connection Re-establishmentComplete) message to the true (true), and transmits the message.

In the system described above, the first base station, the second basestation, and the third station may be configured by an identical basestation. Also, a destination of the logged measurement result from theterminal is not limited to the third base station, but may be anotherbase station with which the terminal can communicate.

[Configuration of Terminal According to Fourth Embodiment]

FIG. 17 is a block diagram of the terminal configuring the wirelesscommunication system according to the fourth embodiment. As illustratedin FIG. 17, the terminal according to the fourth embodiment includes areceiver 401, a controller 403, and a transmitter 405. The controller403 includes a measurement configuration manager 411, a measurementmanager 413, a connection controller 417, an MDT report generator 419,and an MDT report manager 421. Also, the measurement manager 413includes an own cell measurement section 431, a restricted own cellmeasurement section 433, and a neighbor cell measurement section 435.

The receiver 401 receives the system information or the individualcontrol information through a downlink of the cell that is being used bythe terminal according to an instruction from the controller 403. Thereceiver 401 outputs the received system information and individualcontrol information to the controller 403.

The receiver 401 receives a cell specific reference signal (CRS) or areceived signal strong indication (RSSI) of the own cell according to aninstruction from the own cell measurement section 431 installed in themeasurement manager 413 of the controller 403. The receiver 401 outputsthe received CRS or RSSI to the own cell measurement section 431. Also,the receiver 401 receives the CRS or RSSI of the own cell in thespecific resource according to an instruction from the restricted owncell measurement section 433 installed in the measurement manager 413 ofthe controller 403. The receiver 401 outputs the received CRS or RSSI tothe restricted own cell measurement section 433.

The controller 403 outputs the measurement resource restrictioninformation of the own cell, a physical cell identifier (PCI) of the owncell, a frequency of the own cell, information necessary for measurementof the own cell, information necessary for the cell selection, and theinformation necessary for cell reselection to the measurementconfiguration manager 411 from the system information received by thereceiver 401. The controller 403 outputs the information necessary forthe cell selection, and the information necessary for the cellreselection to the connection controller 417. Also, the controller 403,outputs the RRC connection setup message to the connection controller417.

The controller 403 outputs a logged measurement configuration (LoggedMeasurement Configuration), which is one of the individual controlinformation, to the MDT report manager 421. Also, the controller 403outputs a PLMN (Public Land Mobile Network) of the cell connected withthe terminal to the MDT report manager 421. Also, when the controller403 receives the terminal information request message(UEInformationRequest) in which the logged measurement request flag isset to the true (true) in the individual control information, thecontroller 403 instructs the MDT report manager 421 to perform thelogged measurement report.

When the measurement resource restriction for the own cell is input tothe measurement configuration manager 411, the measurement configurationmanager 411 outputs information necessary for the measurement resourcerestriction for the own cell, the PCI of the own cell, the frequency ofthe own cell, and the measurement of the own cell to the restricted owncell measurement section 433. On the other hand, when the measurementresource restriction for the own cell is not input to the measurementconfiguration manager 411, the measurement configuration manager 411outputs information necessary for the PCI of the own cell, the frequencyof the own cell, and the measurement of the own cell to the own cellmeasurement section 431. The measurement configuration manager 411outputs the information necessary for the cell selection and theinformation necessary for the cell reselection to the measurementmanager 413.

The measurement manager 413 manages the RSRP and the RSRQ of the owncell in distinction between the RSRP and the RSRQ measured without theuse of the measurement resource restriction, and the RSRP and the RSRQmeasured with the use of the measurement resource restriction. Themeasurement manager 413 calculates the RSRQ according to the RSRP andthe RSSI which have been input from the own cell measurement section431, and manages the RSRP and the RSRQ as the RSRP and the RSRQ of theown cell which have been measured without the use of the measurementresource restriction. The measurement manager 413 calculates the RSRQaccording to the RSRP and the RSSI which have been input from therestricted own cell measurement section 433, and manages the RSRP andthe RSRQ as the RSRP and the RSRQ of the own cell which have beenmeasured with the use of the measurement resource restriction. When themeasurement manager 413 determines that the measurement of the neighborcell is necessary, according to the managed values, the informationnecessary for the cell selection, and the information necessary for thecell reselection, the measurement manager 413 instructs the neighborcell measurement section 435 to measure the neighbor cell. Themeasurement manager 413 calculates the RSRQ having the PCI of the abovefrequency according to the RSRP, the RSSI, the PCI, and the frequencywhich have been input from the neighbor cell measurement section 435,and manages the RSRP and the RSSI.

In the same frequency, a common value may be used in the RSSI of the owncell and the neighbor cell, which has been measured without beingrestricted to the specific resource. Also, in the RSSI of the own cell,a common value may be used between the RSSI of the own cell measuredwithout being restricted to the specific resource, and the RSSI of theown cell measured with the use of the measurement resource restriction.

Upon receiving an instruction for outputting the measurement result fromthe MDT report manager 421 to the MDT report generator 419, themeasurement manager 413 outputs the measurement result of the own celland the measurement result of the neighbor cell, which have beenmanaged, to the MDT report generator 419. In this situation, if themeasurement results of the own cell are the RSRP and the RSRQ of the owncell which have been measured with the use of the measurement resourcerestriction, the measurement manager 413 outputs the value measured withthe use of the measurement resource restriction to the MDT reportgenerator 419 together.

The measurement manager 413 receives the information from the own cellmeasurement section 431, the restricted own cell measurement section433, or the neighbor cell measurement section 435, updates the managedinformation, and thereafter outputs the updated information to theconnection controller 417.

In order to measure the RSRP or the RSSI of the cell having the PCI ofthe frequency input from the measurement configuration manager 411, theown cell measurement section 431 instructs the receiver 401 to measurethe CRS or the RSSI. In order to remove an influence of fading from thevalue of the CRS or the RSSI which has been input from the receiver 401,the own cell measurement section 431 performs layer 3 filtering on thevalue input from the receiver 401, and outputs the calculated RSRP orRSSI to the measurement manager 413.

In order to measure the RSRP or RSSI of the cell having the PCI of theinput frequency in the resource instructed in the measurement resourcerestriction for the own cell which has been input from the measurementconfiguration manager 411, the restricted own cell measurement section433 instructs the receiver 401 to measure the CRS or the RSSI in theabove resource. The restricted own cell measurement section 433 performsthe layer 3 filtering on the CRS or RSSI input from the receiver 401,and outputs the calculated RSRP or RSSI to the measurement manager 413.

Upon receiving an instruction for measurement of the neighbor cell fromthe measurement manager 413, in order to measure the RSRP or RSSI of thecell having the frequency instructed in the measurement configuration,the neighbor cell measurement section 435 instructs the receiver 401 tomeasure the CRS or the RSSI. The neighbor cell measurement section 435receives the frequency, the PCI and the CRS, or the RSSI from thereceiver 401. The neighbor cell measurement section 435 performs thelayer 3 filtering for each of the cells having the PCI of the abovefrequency, and outputs the calculated RSRP or RSSI to the measurementmanager 413 together with the frequency and the PCI.

The connection controller 417 selects or reselects the cell to beconnected, on the basis of the information input from the measurementmanager 413. When the connection controller 417 determines that theterminal transitions to a connected state, the connection controller 417generates the RRC connection request message, and outputs the generatedmessage to the transmitter 405. Upon receiving the RRC connection setupmessage, the connection controller 417 generates the RRC connectionsetup complete message. In this situation, the connection controller 417inquires of the MDT report manager 421 about whether to hold the loggedmeasurement result to be reported, or not. Upon receiving a responsethat the logged measurement result is available from the MDT reportmanager 421, the connection controller 417 generates the RRC connectionsetup complete message in which the logged measurement available flag isset to the true, and outputs the generated message to the transmitter405.

The MDT report manager 421 instructs the measurement manager to outputthe measurement result managed in the measurement manager to the MDTreport generator 419 on the basis of the logged measurementconfiguration. Only when the PLMN of the cell connected with theterminal matches the RPLMN (Registered PLMN), the MDT report manager 421instructs the measurement manager 413 to output the managed measurementresult to the MDT report generator 419. Upon receiving an inquiry aboutwhether the logged measurement result is available, or not, from theconnection controller 417, the MDT report manager 421 confirms whetherthe measurement result report is present in the MDT report generator419, or not. If the measurement result report is present in the MDTreport generator 419, the MDT report manager 421 returns a response thatthe measurement result report is available. Upon receiving aninstruction for transmitting the logged measurement report from thecontroller 403, the MDT report manager 421 instructs the MDT reportgenerator 419 to output the logged measurement report. The MDT reportmanager 421 generates the terminal information response messageincluding the logged measurement report output from the MDT reportgenerator 419, and outputs the generated message to the transmitter 405.

The MDT report generator 419 generates the logged measurement reportincluding the logged measurement configuration, the value input from themeasurement manager 413, the measured time, and the positioninformation. In this situation, if the measurement result of the owncell input from the measurement manager 413 is the value measured on thebasis of the measurement resource restriction, the MDT report generator419 generates the logged measurement report in which the measurementresource restriction flag is set to the true. The measurement resourcerestriction flag may be configured by 1 bit.

The transmitter 405 transmits the response message to the individualcontrol information, the RRC connection request message, the RRCconnection setup complete message, or the terminal information responsemessage including the logged measurement report.

[Configuration of Base Station According to Fourth Embodiment]

FIG. 18 is a block diagram of the base station configuring the wirelesscommunication system according to the fourth embodiment. As illustratedin FIG. 18, the base station according to the fourth embodiment includesa receiver 451, a controller 453, and a transmitter 455. The controller453 includes a measurement configuration controller 461, a connectioncontroller 463, and an MDT controller 465.

The receiver 451 receives the RRC connection request message, the RRCconnection setup complete message, or the terminal information responsemessage which have been transmitted from the terminal, and output themessage to the controller 453.

When the controller 453 determines that the terminal performs themeasurement of the own cell in the specific resource, the controller 453generates the system information including the measurement resourcerestriction for the own cell. The controller 453 generates the systeminformation including the configuration for cell selection or cellreselection, which has been input from the measurement configurationcontroller 461. The controller 453 instructs the transmitter 455 totransmit the system information. When the controller 453 receives theRRC connection request message, the controller 453 outputs the messageto the connection controller 463. If the logged measurement availableflag is included in the RRC connection setup complete message, and setto the true (true), the controller 453 outputs that the terminal holdsthe logged measurement result to the MDT controller 465. The controller453 outputs the input logged measurement result to the MDT controller465.

The measurement configuration controller 461 of the controller 453generates the configuration for the cell selection or the cellreselection. The configuration for the cell selection or the cellreselection is a threshold value for starting the cell reselectionwithin the frequency of the own cell, or a threshold value for startingthe cell reselection at a frequency other than that of the own cell. Themeasurement configuration controller 461 outputs the configuration forthe cell selection or the cell reselection to the connection controller463.

Upon receiving the RRC connection request message, the connectioncontroller 463 determines whether to permit the connection of theterminal that has transmitted the message, or not. When the connectioncontroller 463 determines that the connection of the above terminal ispermitted, the connection controller 463 generates the RRC connectionsetup message, and outputs the generated message to the transmitter 455.

Upon being notified that the terminal holds the logged measurementresult, the MDT controller 465 determines whether to collect the MDTinformation, or not. If the MDT controller 465 determines to collect thelogged measurement result of the terminal, the MDT controller 465generates the terminal information request message(UEInformationRequest) in which the logged measurement request flag(logMeasAvailable) is set to the true (true), and outputs the generatedmessage to the transmitter 455. Upon receiving the logged measurementreport, the MDT controller 465 determines whether the measurement resultof the own cell included in the above report is the value measured bythe measurement resource restriction, or not. In the determinationmethod, if the terminal includes the measurement resource restrictionflag, the determination is performed according to the flag. Themeasurement resource restriction information may be shared within thenetwork to perform the determination. The MDT controller 465 optimizesthe network on the basis of the MDT report. The MDT controller 465 mayshare the logged measurement report within the network to optimize thenetwork.

The transmitter 455 transmits the individual control information, thesystem information, the RRC connection setup message, or the terminalinformation request message to the terminal.

Subsequently, the operation of the terminal according to the fourthembodiment will be described. FIGS. 19 and 20 are flowchartsillustrating an example of the operation of the terminal according tothe fourth embodiment.

The terminal receives the logged measurement configuration (Loggedmeasurement configuration) by the individual control information in aconnected state (Step S401). Then, the terminal transitions from theconnected state to the idle state (Step S402).

The terminal selects a cell belonging to the idle state (Camp On) (StepS403). If the terminal does not hold the latest system information ofthe own cell, the terminal receives the system information from the owncell, and determines whether the measurement resource restriction forthe own cell is included in the system information, or not (Step S404).If the measurement resource restriction for the own cell is not includedin the system information (no), the terminal allows the operation toproceed to Step S405. On the other hand, if the measurement resourcerestriction for the own cell is included in the system information(yes), the terminal allows the operation to proceed to Step S406.

In Step S405, the terminal measures the own cell without the use of themeasurement resource restriction, and allows the operation to proceed toStep S407. In Step S407, the terminal measures the own cell in theresource of the measurement resource restriction, and allows theoperation to proceed to Step S407.

In Step S407, if the measurement result of the own cell satisfies astart reference of the cell selection or the cell reselection, theterminal starts to measure the neighbor cell according to theconfiguration of the cell selection or the cell reselection. Theterminal periodically logs the measurement result on the basis of thelogged measurement configuration (Step S408). The measurement result ofthe own cell compared with the start reference of the cell reselectionuses the value of the own cell measured with the use of the measurementresource restriction if the own cell is measured by the resource of themeasurement resource restriction, and uses the value of the own cellmeasured without the use of the measurement resource restriction if theown cell is not measured by the resource of the measurement resourcerestriction. The measurement result of the own cell compared with thestart reference of the cell reselection may be always the value obtainedby measuring the own cell without the use of the measurement resourcerestriction. With the above configuration, the start, reference of thecell reselection can be unified between the terminal that cannotunderstand the measurement resource restriction and the terminal thatcan understand the measurement resource restriction.

After Step S408, the terminal allows the operation return to Step S403,the terminal determines the cell reselection on the basis of themeasurement result of the own cell and the neighbor cell (Step S403).Also, if the transition to the connected state is triggered afterlogging the measurement result in Step S408 (Step S409), the terminaldetermines whether to hold the logged measurement result, or not (StepS410). If the terminal does not hold the logged measurement result (no),the terminal is connected to the base station without setting the loggedmeasurement available flag (Step S411). On the other hand, if theterminal holds the logged measurement result (yes), the terminal setsthe logged measurement available flag to the true (true), and transmitsthe above logged measurement available flag at the time of transmission(Step S412). Then, if the terminal receives the logged measurementrequest flag (Step 413), the terminal determines whether to hold thevalue measured in the resource of the measurement resource restriction,or not (Step S414). If the terminal holds the value measured in theresource of the measurement resource restriction (yes), the operationproceeds to Step S415. If the terminal does not hold the value measuredin the resource of the measurement resource restriction (no), theoperation proceeds to Step S416.

In Step S415, the terminal generates the logged measurement report inwhich the measurement resource restriction flag is set to the true, inthe value obtained by measuring the own cell in the resource of themeasurement resource restriction. The measurement resource restrictionflag may be configured by 1 bit. On the other hand, in Step S416, theterminal generates the logged measurement report by the value measuredwithout the use of the measurement resource restriction. After Steps 415and S416, the operation proceeds to Step S417. In Step S417, theterminal transmits the logged measurement report generated in Step S415or S416 to the base station.

As described above, according to this embodiment, the terminal includesthe value of the own cell measured with the use of the measurementresource restriction in the logged measurement report. For that reason,the base station that has received the logged measurement report canprecisely grasp the state of the cell in the terminal even under theenvironment where the ABS is used. In particular, if the terminal islocated in the vicinity of the CSG cell not permitted to be accessed, tomeasure the cell permitted to be accessed is more important because aconnectivity of the terminal with the cell can be enhanced. With the useof this embodiment, the terminal can enhance the connectivity with theown cell, and can enhance the connectivity of the terminal with thecell. Also, if the terminal is connected to the cell having the cellcoverage expanded more than that of the conventional art, the own cellis measured with the use of the ABS of the neighbor cell, thereby beingcapable of precisely measuring the state of the cell to which thenetwork is to maintain the connection.

Another Example 1

In the above fourth embodiment, a case in which the measurement resourcerestriction for the own cell is included in the system information ofthe own cell has been described. Instead, the measurement resourcerestriction for the neighbor cell may be included. That is, if themeasurement resource restriction for the neighbor cell is included inthe system information for the own cell, the terminal logs the valueobtained by measuring the neighbor cell by the resource of themeasurement resource restriction, and includes the logged value in thelogged measurement report. The terminal sets the measurement resourcerestriction flag to the true for each of the cells in the value measuredby the resource of the measurement resource restriction. The measurementresource restriction flag may be provided for not each cell but eachfrequency. The measurement resource restriction for the neighbor cellmay be applied to only the specific neighbor cell by being informed oftogether with the neighbor cell list. In this case, the measurementresource restriction flag is set for each of the cells. The terminallogs the value measured without the use of the measurement resourcerestriction for the cell having no measurement resource restriction, andincludes that value in the logged measurement report. With thisconfiguration, in the case where the cell coverage of the terminal isexpanded more than that of the conventional art for the operation,because the neighbor cell can be measured taking the ABS intoconsideration, the network can precisely collect the information of thecell when the ABS is applied.

Another Example 2

In the above fourth embodiment, the case in which the measurementresource restriction for the own cell is included in the systeminformation of the own cell has been described. Instead, both of themeasurement resource restriction for the own cell and the measurementresource restriction for the neighbor cell may be included in the systeminformation of the own cell. That is, if the both of the measurementresource restrictions are included in the system information of the owncell, the terminal logs the value obtained by measuring the own cell bythe resource of the measurement resource restriction for the own cell,logs the value obtained by measuring the neighbor cell by the resourceof the measurement resource restriction for the neighbor cell, andincludes those values in the logged measurement report. The terminal mayconfigure the measurement resource restriction for the own cell and themeasurement resource restriction for the neighbor cell at the same time.With the above configuration, in the case where the cell coverage of theterminal is to be expanded more than that of the conventional art forthe operation, because the neighbor cell can be measured taking the ABSinto consideration, the network can precisely collect the information ofthe cell when the ABS is applied.

Another Example 3

In the above fourth embodiment, the case in which the measurementresource restriction for the own cell is included in the systeminformation of the own cell has been described. Instead, the measurementresource restriction included in the system information of the own cellmay be applied to both of the own cell and the neighbor cell on the samefrequency. That is, the terminal logs the values obtained by measuringthe own cell and the neighbor cell with the use of the measurementresource restriction included in the system information of the own cell,and includes the respective values in the logged measurement report.With the above configuration, the terminal can grasp the states of theown cell and the neighbor cell at the same timing. The terminal logs thevalue measured without the use of the measurement resource restrictionfor the cell having no measurement resource restriction, and includesthat value in the logged measurement report. With the aboveconfiguration, in the case where the cell coverage of the terminal is tobe expanded more than that of the conventional art for the operation,because the neighbor cell can be measured taking the ABS intoconsideration, the network can precisely collect the information of thecell when the ABS is applied.

Another Example 4

In the above fourth embodiment, the case in which the measurementresource restriction for the own cell is included in the systeminformation of the own cell has been described. Instead, the ABSinformation of the own cell may be included. In this case, the terminallogs the value obtained by measuring the neighbor cell with the use ofthe ABS of the own cell, and includes that value in the loggedmeasurement report. If the ABS information of the own cell is notincluded in the system information of the own cell, the terminal logsthe value obtained by measuring the neighbor cell without the use of themeasurement resource restriction, and includes that value in themeasurement result report. The terminal logs the value obtained bymeasuring the own cell without the use of the measurement resourcerestriction, and includes the logged value in the measurement resultreport. Further, the terminal sets a flag indicative of the measurementtaking the ABS into consideration (measurement resource restrictionflag) to the true, for the neighbor cell measured with the use of theABS of the own cell.

In the above fourth embodiment, the case in which the measurementresource restriction for the own cell is included in the systeminformation of the own cell has been described. Instead, the cell listand the ABS information for each cell may be included. In this case, theterminal calculates the resource (measurement resource restriction) inwhich the interference is reduced for each of the cells from the celllist and the ABS information of each cell, measures the own cell and theneighbor cell with the use of that resource, and includes the respectivemeasured values in the logged measurement report. The terminal logs thevalue measured without the use of the measurement resource restrictionfor the cell determined to be measured without the use of themeasurement resource restriction, and includes the logged value in thelogged measurement report. In this case, the terminal sets themeasurement resource restriction flag to the true for the cell measuredwith the use of the measurement resource restriction. Only the own cellmay be measured with the use of the measurement resource restriction.

In the above fourth embodiment, and the other examples 1 to 4, a flag(measurement resource restriction consideration flag) of whether themeasurement resource restriction is taken into consideration, or not,may be included in the logged measurement configuration (LoggedMeasurement Configuration). The measurement resource restrictionconsideration flag is configured by 1 bit. If the measurement resourcerestriction consideration flag is set to the true (true), the terminalperforms the operation of the fourth embodiment. On the other hand, ifthe measurement resource restriction consideration flag is not set, theterminal always logs the value obtained by measuring the own cellwithout the use of the measurement resource restriction. With the aboveconfiguration, in the case where the terminal that is in the idle statemeasures the own cell with the use of the measurement resourcerestriction while the terminal measures the own cell without the use ofthe measurement resource restriction, the terminal can designate whichof the values is to be included in the logged measurement result, andcan precisely acquire the information to be known by the network.

In the case where the terminal measures the own cell with the use of themeasurement resource restriction while the terminal measures the owncell without the use of the measurement resource restriction, themeasurement result of the own cell compared with the start reference ofthe cell reselection may be always a value obtained by measuring the owncell without the use of the measurement resource restriction. With theabove operation, the start reference of the cell reselection can beunified between the terminal that cannot understand the measurementresource restriction and the terminal that can understand themeasurement resource restriction.

In the above fourth embodiment, the terminal receives the systeminformation from only the own cell. Alternatively, the terminal mayreceive the respective system information from the own cell and theneighbor cell. In this situation, the terminal acquires the ABSinformation from the system information of the respective cells,calculates the resource (measurement resource restriction) in which theinterference is reduced for each of the cells, logs the respectivevalues obtained by measuring the own cell and the neighbor cell with theuse of the resource, and includes the respective values in themeasurement result report. In this situation, the terminal sets themeasurement resource restriction flag to the true for the cell measuredwith the use of the measurement resource restriction. The terminal maymeasure only the own cell with the use of the measurement resourcerestriction. In the cell determined to be measured without the use ofthe measurement resource restriction, the terminal logs the valuemeasured without the use of the measurement resource restriction, andincludes the logged value in the logged measurement report.

The measurement resource restriction consideration flag described abovemay be configured by 2 bits. The measurement resource restrictionconsideration flag represented by 2 bits can express, for example, thefollowing three patterns.

00: The ABS is not taken into consideration.

01: The ABS information is received from only the own cell.

10: The ABS information is received from the own cell and the neighborcell.

If the measurement resource restriction consideration flag included inthe logged measurement configuration is “00”, the terminal logs thevalues obtained by measuring the own cell and the neighbor cell withoutthe use of the measurement resource restriction, and includes thosevalues in the logged measurement report. Also, if the measurementresource restriction consideration flag included in the loggedmeasurement configuration is “01”, the terminal attempts to receive theABS information from only the own cell, and if the ABS information isincluded, the terminal logs the value obtained by measuring the neighborcell by the resource of the ABS of the own cell, and includes the valuein the measurement result report. Also, if the measurement resourcerestriction consideration flag included in the logged measurementconfiguration is “10”, the terminal attempts to receive the ABSinformation from the own cell and the neighbor cell, and if the ABSinformation is included, the terminal calculates the measurementresource for each of the cells, and includes the values measured withthe use of the measurement resource restriction for the cells determinedto be subjected to the measurement resource restriction in the loggedmeasurement report. With the above operation, the base station canobtain only the necessary information.

In the fourth embodiment, the case in which the measurement of the owncell is performed with the use of the measurement resource restrictionincluded in the system information of the own cell has been described.Instead, the cell of the frequency (Inter-frequency) different from thatof the own cell may be measured with the use of the measurement resourcerestriction included in the system information of the own cell. That is,if the measurement resource restriction is included in the systeminformation of the own cell, the terminal logs the respective valuesobtained by measuring the own cell, the neighbor cell, and the neighborcell of the frequency different from that of the own cell with the useof the measurement resource restriction included in the systeminformation of the own cell, and includes the respective values in thelogged measurement report. On the other hand, if the measurementresource restriction is not included in the system information of theown cell, the terminal logs the respective values obtained by measuringthe respective cells without the use of the measurement resourcerestriction, and includes the respective values in the loggedmeasurement report. In this case, the terminal sets the measurementresource restriction flag to the true (true) for the cells measured withthe use of the measurement resource restriction.

In the fourth embodiment, the case in which the measurement of the owncell is performed with the use of the measurement resource restrictionincluded in the system information of the own cell has been described.Instead, the terminal may include the ABS information of the own cell inthe system information of the own cell, and measure the cell of thefrequency (Inter-frequency) different from that of the own cell on thebasis of the ABS information of the own cell. That is, if the ABSinformation of the own cell is included in the system information of theown cell, the terminal logs the respective values obtained by measuringthe own cell, the neighbor cell, and the neighbor cell of the frequencydifferent from that of the own cell with the use of the ABS of the owncell, and includes the respective values in the logged measurementresult report. On the other hand, if the ABS information of the own cellis not included in the system information of the own cell, the terminallogs the respective values obtained by measuring the respective cellswithout the use of the measurement resource restriction, and includesthe respective values in the logged measurement report. In this case,when the same ABS is used between the frequencies, even if the systeminformation is not acquired at another frequency, the ABS of thedifferent frequency can be taken into consideration.

In the above fourth embodiment, and the other examples 1 to 4, a flag(different frequency consideration flag) taking the frequency differentfrom that of the own cell into consideration may be included in thelogged measurement configuration (Logged Measurement Configuration). Ifthe different frequency consideration flag is set to the true (true),the terminal logs the value obtained by measuring the neighbor cell ofthe frequency different from that of the own cell with the use of theABS information of the own cell included in the system information ofthe own cell, and includes the value in the logged measurement report.On the other hand, if the different frequency consideration flag is notset to the true, the terminal logs the value measured without the use ofthe measurement resource restriction for the neighbor cell of thefrequency different from that of the own cell, and includes the value inthe logged measurement report. With the above configuration, because theABS is taken into consideration only when the network wants theconsideration of the ABS for the different frequency, the powerconsumption can be reduced.

In the above fourth embodiment, the case in which the measurement of theown cell is performed with the use of the measurement resourcerestriction included in the system information of the own cell has beendescribed. In the frequency other than that of the own cell, theterminal receives the system information from the cell high in thereceived power, logs the respective values obtained by measuring thecell and the neighbor cell of that cell with the use of the measurementresource restriction included in the system information, and includesthe respective values in the logged measurement report. The measurementresource restriction may be common at the identical frequency, or may beset in distinction between the own cell and the neighbor cell, or may beset for each of the neighbor cells by setting the measurement resourcerestriction for the neighbor cells together with the cell list. Thefrequency of the own cell can be applied with the above fourthembodiment and the other examples 1 to 4. With the above configuration,because the different frequency can be measured taking the measurementresource restriction into consideration, the network can know the statewhen the measurement resource restriction is applied in a plurality offrequencies.

The flag (different frequency consideration flag) taking the frequencydifferent from that of the own cell into consideration may be includedin the logged measurement configuration. If the different frequencyconsideration flag is set to the true (true), the terminal receives thesystem information from the cell high in the received power at afrequency different from that of the own cell, logs the respectivevalues obtained by measuring the cell and the neighbor cell of that cellwith the use of the measurement resource restriction included in thesystem information, and includes the respective values in the loggedmeasurement report. On the other hand, if the different frequencyconsideration flag is not set to the true, the terminal logs the valuemeasured without the use of the measurement resource restriction for theneighbor cell of the frequency different from that of the own cell, andincludes the logged value in the logged measurement report.

In the above fourth embodiment, the case in which the measurement of theown cell is performed with the use of the measurement resourcerestriction included in the system information of the own cell has beendescribed. In the frequency other than that of the own cell, theterminal receives the system information from the respective cells, logsthe values obtained by measuring the respective cells, and includes therespective values in the logged measurement report. The loggedmeasurement configuration may include the flag (different frequencyconsideration flag) taking the frequency different from that of the owncell into consideration. If the different frequency consideration flagis set to the true (true), the terminal receives the system informationfrom the respective cells at the frequency different from that of theown cell, logs the value obtained by measuring the cell with the use ofthe measurement resource restriction included in the system information,and includes the logged value in the logged measurement report. On theother hand, if the different frequency consideration flag is not set tothe true, the terminal logs the value measured without the use of themeasurement resource restriction for the neighbor cell of the frequencydifferent from that of the own cell, and includes the logged value inthe logged measurement report. The frequency of the own cell can beapplied with the fourth embodiment and the other examples 1 to 4.

In the above fourth embodiment, the case in which the measurement of theown cell is performed with the use of the measurement resourcerestriction included in the system information of the own cell has beendescribed. In the frequency other than that of the own cell, theterminal receives the system information from the cell high in thereceived power, logs the respective values obtained by measuring thecell and the neighbor cell of that cell with the use of the ABSinformation of the above cells included in the system information, andincludes the respective values in the logged measurement report. Thesystem information may include the cell list and the ABS information ofthe respective cells. In this case, the terminal calculates the resourcein which the interference is reduced for each of the cells, logs thevalue measured with the use of that resource, and includes the loggedvalue in the logged measurement report. The frequency of the own cellcan be applied with the above fourth embodiment and the other examples 1to 4.

The flag (different frequency consideration flag) taking the frequencydifferent from that of the own cell into consideration may be includedin the logged measurement configuration. If the different frequencyconsideration flag is set to the true (true), the terminal receives thesystem information from the cell high in the received power at afrequency different from that of the own cell, logs the respectivevalues obtained by measuring the cell and the neighbor cell of that cellwith the use of the ABS information included in the system information,and includes the respective values in the logged measurement report. Onthe other hand, if the different frequency consideration flag is not setto the true, the terminal logs the value measured without the use of themeasurement resource restriction for the neighbor cell of the frequencydifferent from that of the own cell, and includes the logged value inthe logged measurement report. With the above configuration, because theABS is taken into consideration only when the network wants theconsideration of the ABS for the different frequency, the powerconsumption can be reduced.

The above first to third embodiments can be used in combination. Forexample, when the second embodiment and the third embodiment are used incombination, when the terminal configures the measurement resourcerestriction of the own cell, and when the operation of the thirdembodiment is performed, and the terminal does not configure themeasurement resource restriction of the own cell, the operation of thesecond embodiment is performed. With this configuration, the RLF reportcorresponding to the topology of the network can be performed.

In the present invention, the reason that the measurement resourcerestriction is used for the measurement of the RSRP is because when themeasurement precision of the reference signal is degraded by theinfluence of an interference power, the reference signal is measuredwith the low interference power, to thereby enhance the precision of theRSRP. On the other hand, the reason that the measurement resourcerestriction is used for measurement of the RSRQ is because there is adifference in the interference power between the ABS and the resourceother than the ABS, and therefore the terminal measures the RSRQ in theresource actually used. For that reason, in the above respectiveembodiments, only the RSRQ may be measured with the use of themeasurement resource restriction, or only the RSRP may be measured withthe use of the measurement resource restriction. With the aboveconfiguration, the measurement can be performed taking the environmentinto consideration while leaving the degree of freedom of themeasurement. In this case, the measurement resource restriction may beconfigured for only the RSRQ or only the RSRP in advance. Also, in themeasurement configuration, a target of the measurement resourcerestriction may be instructed by a flag of 1 bit. For example, themeasurement resource restriction is intended for both of the RSRP andthe RSRQ if there is no instruction, and the measurement resourcerestriction is intended for only the RSRQ if there is the instruction.Also, in the measurement configuration, the target of the measurementresource restriction may be instructed by a flag of 2 bits. For example,the measurement resource restriction is intended for only the RSRP, onlythe RSRQ, or both of the RSRP and the RSRQ according to the instruction.With the above configuration, because the target of the measurementresource restriction can be changed according to the environment, themeasurement can be efficiently performed. Also, in the transmission ofthe RLF report request to the terminal from the base station, the RLFreport taking the measurement resource restriction into considerationmay be transmitted according to the instruction. With the aboveconfiguration, the base station can obtain the necessary information.The instruction method may indicate whether to transmit the valuemeasured with the use of the measurement resource restriction, or not,for example, by using the flag. Also, an instruction may be performed totransmit the value obtained by measuring only the RSRQ with the use ofthe measurement resource restriction, for example, by the flag (1 bit).Also, an instruction may be performed to preferentially transmit thevalue obtained by measuring only the RSRQ, only the RSRP, or both of theRSRP and the RSRQ with the use of the measurement resource restriction,for example, by the flag (2 bits). Also, an instruction may be performedto include both of the measured value using the measurement resourcerestriction and the measured value using no measurement resourcerestriction in the RLF report by the RLF report request. For example, ifthere is the instruction, only the measured value of the measurementresource restriction is included in the RLF report, and if there is noinstruction, both the measured values are included in the RLF report.

The present invention can be also applied to a carrier aggregation(Carrier Aggregation: CA). In the carrier aggregation, the terminal hasa plurality of own cells, which includes one primary cell (Primary Cell:PCell) and one or more secondary cells (Secondary Cell: SCell). Theprimary cell is one of the own cells, which is a cell of the frequencyused at the time of first connection establishment or connectionreestablishment, or a cell instructed at the time of handover. On theother hand, the secondary cell is one of the own cells which is a cellconfigured by the wireless communication device. For example, theterminal includes the measured value of the primary cell in which thepresent invention is applied to the RLF report. The RLF of the terminalis determined according to the state of the primary cell, as a result ofwhich the base station can grasp the state of the most important primarycell. Also, for example, the terminal may include the measured value ofthe primary cell in which the present invention is applied to the RLFreport, and the measured value of the secondary cell that detects theRLF. With this configuration, the base station can grasp the state inwhich the RLF occurs. Also, for example, the terminal includes themeasured value of the primary cell which is applied with the presentinvention, and the measured value of the secondary cell which is appliedwith the present invention, in the RLF report. As a result, the basestation can grasp the states of all the own cells used by the terminal.Also, the terminal may include the measured value that is not appliedwith the present invention for the own cell having no value which isapplied with the present invention. As a result, the base station cangrasp the states of the own cells that have been used by the terminal.

If the terminal performs the carrier aggregation at the time of the RLF,the terminal may include the information (a cell global identity (CellGlobal Identity: CGI), or the frequency and a physical cell identity(Physical Cell Identity: PCT)) on the secondary cell configured at thetime of generating the RLF. Because the base station that has receivedthe above RLF report can explicitly grasp which is the secondary cellconfigured in the terminal, the base station can more precisely graspthe state of the terminal when the radio link failure (RLF) isgenerated.

The present invention can be also applied to an MDT (Minimization DriveTest) function.

In the above embodiments, the method using the CRS is described, but thepresent invention may use a method using the reference signal other thanthe CRS. For example, the CRS may be replaced with the reference signalspecific to the CSI-RS or the terminal.

The present invention is also useful to a case having a feature in whicha specific subframe is different from another subframe.

In the above respective embodiments, the example in which the presentinvention is configured by hardware has been described. The presentinvention can be realized by software in association with the hardware.

Also, the respective functional blocks used in the description of therespective embodiments are realized as an LSI that is typically anintegrated circuit. Each of those functional blocks may be configured byone chip, or a part or all of those functional blocks may be integratedinto one chip. In this example, the chip is called the LSI, but may becalled IC, system LSI, super LSI, or ultra LSI due to a difference inintegration.

Also, a technique of the integrated circuit is not limited to the LSI,but may be realized by a dedicated circuit or a general-purposeprocessor. There may be used an FPGA (field programmable gate array)that is programmable after manufacturing an LSI, or a reconfigurableprocessor that can reconfigure the connection or setting of a circuitcell within the LSI.

Further, if a technology for integration circuit which is substitutedfor the LSI appears due to the development of the semiconductortechnology or another technology derived therefrom, the functionalblocks may be integrated by that technology. A biotechnology may beapplied.

The above embodiments have been described as the antenna, however, thesame is applicable even to an antenna port. The antenna port (Antennaport) means a logical antenna configured by one or plural physicalantennas. That is, the antenna port does not always mean one physicalantenna, but may mean an array antenna configured by plural antennas.For example, in the LTE (Long Term Evolution), the number of physicalantennas configuring the antenna port is not specified, but the antennaport is specified as the minimum unit by which the base station cantransmit different reference signals (Reference signal). Also, theantenna port may be specified as the minimum unit by which the weightingof a precoding vector (Precoding vector) is multiplied.

The present invention has been described in detail and with reference tothe specific embodiments, but one skilled in the art could devisevariations without departing from the spirit and scope of the inventiondisclosed therein.

The present application is based on Japanese Patent Application No.2011-030036 filed on Feb. 15, 2011, and Japanese Patent Application No.2011-082183 filed on Apr. 1, 2011, the contents of which areincorporated herein by reference.

INDUSTRIAL APPLICABILITY

The wireless communication terminal, the wireless communication basestation, and the wireless communication system according to the presentinvention are useful as the wireless communication system that reducesthe traffic volume to be transmitted to the wireless communicationterminal, or reduces the transmission power of the wireless signal, aswell as the wireless communication terminal and the wirelesscommunication base station which are used in the wireless communicationsystem.

REFERENCE SIGNS LIST

-   -   101, 201, 301, 401: receiver    -   103, 203, 303, 403: controller    -   105, 405: transmitter    -   111, 211, 311, 411: measurement configuration manager    -   113, 213, 313, 413: measurement manager    -   115: RLM controller    -   117: reconnection controller    -   417: connection controller    -   119, 219, 319: RLF report generator    -   419: MDT report generator    -   121: RLF report manager    -   421: MDT report manager    -   131, 431: own cell measurement section    -   133, 433: restricted own cell measurement section    -   135, 235, 335, 435: neighbor cell measurement section    -   237, 337: restricted neighbor cell measurement section    -   151, 451: receiver    -   153, 253, 453: controller    -   155, 455: transmitter    -   161, 261, 461: measurement configuration controller    -   163: reconnection controller    -   463: connection controller    -   165, 265: RLF controller    -   465: MDT controller

The invention claimed is:
 1. A wireless communication terminalcomprising: a receiver which, in operation, receives control informationfor generating a report related to a measurement result of acommunication cell provided by a wireless communication base station; acontroller which, in operation, monitors a state of a radio link with anown cell, which is a communication cell that is in connection with thewireless communication terminal; performs a measurement on a downlinksignal in the communication cell provided by the wireless communicationbase station; and generates a radio link failure report including ameasurement result when a radio link failure occurs in the own cell; anda transmitter which, in operation, transmits the radio link failurereport, wherein if the control information includes an instruction torestrict measurement to a part of radio resources, after the radio linkfailure occurs the controller generates the radio link failure reportincluding a measurement result in the part of radio resources.
 2. Thewireless communication terminal according to claim 1, wherein the partof radio resources includes a subframe, in which the wirelesscommunication base station transmits no downlink signals, or transmitsdownlink signals at a reduced transmission power in the own cell.
 3. Thewireless communication terminal according to claim 1, wherein the partof radio resources includes a subframe, in which no downlink signals aretransmitted, or downlink signals are transmitted at a low transmissionpower in a communication cell that neighbors the own cell.
 4. Thewireless communication terminal according to claim 1, wherein if thecontrol information related to the own cell includes the instruction torestrict measurement to the part of radio resources, the controllergenerates the radio link failure report including a measurement resultin the part of radio resources in a communication cell to that neighborsthe own cell.
 5. A wireless communication terminal comprising: areceiver which, in operation, receives from a wireless communicationbase station control information for restricting radio resources in anown cell or a neighbor cell to be measured; a controller which, inoperation, receives a reference signal in the own cell or the neighborcell, and performs a measurement on a downlink signal; and generates aradio link failure report including a result of the measurement; and atransmitter which, in operation, transmits the radio link failurereport, wherein if the control information includes an instruction torestrict measurement of the own cell or the neighbor cell to a part ofthe radio resources, the controller generates the radio link failurereport including a measurement result in the part of the radio resourcesof the own cell or the neighbor cell.
 6. The wireless communicationterminal according to claim 5, wherein the controller, in operation,generates a radio link failure report that sets, to a true, a flagindicative of a measurement result measured according to the instructionwhen the own cell or the neighbor cell is measured according to theinstruction to restrict measurement to the part of the radio resources.7. A wireless communication base station comprising: a receiver which,in operation, receives from a wireless communication terminal a radiolink failure report including a measurement result restricted to a partof radio resources; and a controller which, in operation, determineswhether or not the received radio link failure report includes ameasurement result restricted to the part of radio resources.
 8. Awireless communication base station comprising: a receiver which, inoperation, receives from a wireless communication terminal a radio linkfailure report including a measurement result in an own cell or aneighbor cell, which is restricted to a part of radio resources; and acontroller which, in operation, determines whether or not the receivedradio link failure report includes a measurement result restricted tothe part of radio resources.
 9. A wireless communication systemincluding a wireless communication terminal and first and secondwireless communication base stations, wherein the first wirelesscommunication base station, in operation, transmits control informationreferred to by the wireless communication terminal in generating areport related to a measurement result of a communication cell providedby the first wireless communication base station, the wirelesscommunication terminal includes: a receiver which, in operation,receives the control information; a controller which, in operation,monitors a state of a radio link with an own cell, which is acommunication cell that is in connection with the wireless communicationterminal; performs a measurement on a downlink signal in thecommunication cell provided by the first wireless communication basestation; and generates a radio link failure report including ameasurement result when a radio link failure occurs in the own cell; anda transmitter which, in operation, transmits the radio link failurereport, wherein if the control information received from the firstwireless communication base station includes an instruction to restrictmeasurement to a part of radio resources, after the radio link failureoccurs the controller generates the radio link failure report includinga measurement result in the part of radio resources, and the secondwireless communication base station includes: a receiver which, inoperation, receives from the wireless communication terminal, the radiolink failure report including a measurement result restricted to thepart of radio resources; and a controller which, in operation,determines whether or not the received radio link failure reportincludes a measurement restricted to the part of radio resources.
 10. Awireless communication system including a wireless communicationterminal and first and second wireless communication base stations,wherein the first wireless communication base station, in operation,transmits to the wireless communication terminal control information forrestricting radio resources in an own cell or a neighbor cell to bemeasured by the wireless communication terminal, the own cell beingprovided by the first wireless communication base station, the wirelesscommunication terminal includes: a receiver which, in operation,receives the control information; a controller which, in operation,receives a reference signal in the communication cell provided by thefirst wireless communication base station, and performs a measurement ona downlink signal; and generates a radio link failure report including aresult of the measurement; and a transmitter which, in operation,transmits the radio link failure report, wherein if the controlinformation received from the first wireless communication base stationincludes an instruction to restrict measurement of the own cell or theneighbor cell to a part of the radio resources, the controller generatesthe radio link failure report including a measurement result in the partof the radio resources of the own cell or the neighbor cell, and thesecond wireless communication base station includes: a receiver which,in operation, receives from the wireless communication terminal, theradio link failure report including a measurement result in the own cellor the neighbor cell, which is restricted to the part of the radioresources; and a controller which, in operation, determines whether ornot the received radio link failure report includes a measurement resultrestricted to the part of radio resources.
 11. A reporting method of awireless communication terminal, the reporting method comprising:receiving control information for generating a report related to ameasurement result of a communication cell provided by a wirelesscommunication base station; monitoring a state of a radio link with anown cell, which is a communication cell that is in connection with thewireless communication terminal; performing a measurement on a downlinksignal in the communication cell provided by the wireless communicationbase station; if the control information includes an instruction torestrict measurement to a part of radio resources, after a radio linkfailure occurs in the own cell, generating a radio link failure reportincluding a measurement result in the part of radio resources; andtransmitting the radio link failure report.
 12. A reporting method of awireless communication terminal, the reporting method comprising:receiving from a wireless communication base station control informationfor restricting radio resources in an own cell or a neighbor cell to bemeasured; receiving a reference signal in the own cell or the neighborcell, and performing a measurement on a downlink signal; generating aradio link failure report including a result of the measurement; andtransmitting the radio link failure report, wherein if the controlinformation includes an instruction to restrict measurement of the owncell or the neighbor cell to a part of the radio resources, the radiolink failure report is generated to include a measurement result in thepart of the radio resources of the own cell or the neighbor cell.